Add xreflabels to /contrib manuals so links appear correct. Also update

README.links to explain xref properly.

doc/src/sgml/README.links

@@ -7,8 +7,8 @@ Intra-document Linking
 ----------------------
 
 <xref>
-	use to get link text from the title of the target link; has no
-	close tag
+	use to get chapter/section # from the title of the target
+	link, or xreflabel if defined at the target; has no close tag
 	http://www.oasis-open.org/docbook/documentation/reference/html/xref.html
 
 <link>
@@ -28,7 +28,8 @@ External Linking
 
 <ulink>
 	like <link>, but uses a URL (not a document target);  requires
-	</ulink>; if no text is specified, the URL appears as the link text
+	</ulink>; if no text is specified, the URL appears as the link
+	text
 	http://www.oasis-open.org/docbook/documentation/reference/html/ulink.html
 
 url=
@@ -40,4 +41,5 @@ Guidelines
 
 o  If you want to supply text, use <link>, else <xref>
 o  Do not use text with <ulink> so the URL appears in printed output
-o  You can supply text at the target location with 'xreflabel'
+o  Specific nouns like GUC variables, SQL commands, and contrib modules
+   usually have xreflabels

doc/src/sgml/adminpack.sgml

 <!-- doc/src/sgml/adminpack.sgml -->
 
-<sect1 id="adminpack">
+<sect1 id="adminpack" xreflabel="adminpack">
  <title>adminpack</title>
 
  <indexterm zone="adminpack">

doc/src/sgml/auth-delay.sgml

 <!-- doc/src/sgml/auth-delay.sgml -->
 
-<sect1 id="auth-delay">
+<sect1 id="auth-delay" xreflabel="auth_delay">
  <title>auth_delay</title>
 
  <indexterm zone="auth-delay">

doc/src/sgml/auto-explain.sgml

 <!-- doc/src/sgml/auto-explain.sgml -->
 
-<sect1 id="auto-explain">
+<sect1 id="auto-explain" xreflabel="auto_explain">
  <title>auto_explain</title>
 
  <indexterm zone="auto-explain">

doc/src/sgml/btree-gin.sgml

 <!-- doc/src/sgml/btree-gin.sgml -->
 
-<sect1 id="btree-gin">
+<sect1 id="btree-gin" xreflabel="btree_gin">
  <title>btree_gin</title>
 
  <indexterm zone="btree-gin">

doc/src/sgml/btree-gist.sgml

 <!-- doc/src/sgml/btree-gist.sgml -->
 
-<sect1 id="btree-gist">
+<sect1 id="btree-gist" xreflabel="btree_gist">
  <title>btree_gist</title>
 
  <indexterm zone="btree-gist">

doc/src/sgml/chkpass.sgml

 <!-- doc/src/sgml/chkpass.sgml -->
 
-<sect1 id="chkpass">
+<sect1 id="chkpass" xreflabel="chkpass">
  <title>chkpass</title>
 
  <indexterm zone="chkpass">

doc/src/sgml/citext.sgml

 <!-- doc/src/sgml/citext.sgml -->
 
-<sect1 id="citext">
+<sect1 id="citext" xreflabel="citext">
  <title>citext</title>
 
  <indexterm zone="citext">

doc/src/sgml/contrib-spi.sgml

 <!-- doc/src/sgml/contrib-spi.sgml -->
 
-<sect1 id="contrib-spi">
+<sect1 id="contrib-spi" xreflabel="spi">
  <title>spi</title>
 
  <indexterm zone="contrib-spi">

doc/src/sgml/cube.sgml

 <!-- doc/src/sgml/cube.sgml -->
 
-<sect1 id="cube">
+<sect1 id="cube" xreflabel="cube">
  <title>cube</title>
 
  <indexterm zone="cube">

doc/src/sgml/dblink.sgml

 <!-- doc/src/sgml/dblink.sgml -->
 
-<sect1 id="dblink">
+<sect1 id="dblink" xreflabel="dblink">
  <title>dblink</title>
 
  <indexterm zone="dblink">

doc/src/sgml/dict-int.sgml

 <!-- doc/src/sgml/dict-int.sgml -->
 
-<sect1 id="dict-int">
+<sect1 id="dict-int" xreflabel="dict_int">
  <title>dict_int</title>
 
  <indexterm zone="dict-int">

doc/src/sgml/dict-xsyn.sgml

 <!-- doc/src/sgml/dict-xsyn.sgml -->
 
-<sect1 id="dict-xsyn">
+<sect1 id="dict-xsyn" xreflabel="dict_xsyn">
  <title>dict_xsyn</title>
 
  <indexterm zone="dict-xsyn">

doc/src/sgml/dummy-seclabel.sgml

 <!-- doc/src/sgml/dummy_seclabel.sgml -->
 
-<sect1 id="dummy-seclabel">
+<sect1 id="dummy-seclabel" xreflabel="dummy_seclabel">
  <title>dummy_seclabel</title>
 
  <indexterm zone="dummy-seclabel">

doc/src/sgml/earthdistance.sgml

 <!-- doc/src/sgml/earthdistance.sgml -->
 
-<sect1 id="earthdistance">
+<sect1 id="earthdistance" xreflabel="earthdistance">
  <title>earthdistance</title>
 
  <indexterm zone="earthdistance">

doc/src/sgml/file-fdw.sgml

 <!-- doc/src/sgml/file-fdw.sgml -->
 
-<sect1 id="file-fdw">
+<sect1 id="file-fdw" xreflabel="file_fdw">
  <title>file_fdw</title>
 
  <indexterm zone="file-fdw">

doc/src/sgml/fuzzystrmatch.sgml

 <!-- doc/src/sgml/fuzzystrmatch.sgml -->
 
-<sect1 id="fuzzystrmatch">
+<sect1 id="fuzzystrmatch" xreflabel="fuzzystrmatch">
  <title>fuzzystrmatch</title>
 
  <indexterm zone="fuzzystrmatch">

doc/src/sgml/hstore.sgml

 <!-- doc/src/sgml/hstore.sgml -->
 
-<sect1 id="hstore">
+<sect1 id="hstore" xreflabel="hstore">
  <title>hstore</title>
 
  <indexterm zone="hstore">

doc/src/sgml/intagg.sgml

 <!-- doc/src/sgml/intagg.sgml -->
 
-<sect1 id="intagg">
+<sect1 id="intagg" xreflabel="intagg">
  <title>intagg</title>
 
  <indexterm zone="intagg">

doc/src/sgml/intarray.sgml

 <!-- doc/src/sgml/intarray.sgml -->
 
-<sect1 id="intarray">
+<sect1 id="intarray" xreflabel="intarray">
  <title>intarray</title>
 
  <indexterm zone="intarray">

doc/src/sgml/isn.sgml

 <!-- doc/src/sgml/isn.sgml -->
 
-<sect1 id="isn">
+<sect1 id="isn" xreflabel="isn">
  <title>isn</title>
 
  <indexterm zone="isn">

doc/src/sgml/lo.sgml

 <!-- doc/src/sgml/lo.sgml -->
 
-<sect1 id="lo">
+<sect1 id="lo" xreflabel="lo">
  <title>lo</title>
 
  <indexterm zone="lo">

doc/src/sgml/ltree.sgml

 <!-- doc/src/sgml/ltree.sgml -->
 
-<sect1 id="ltree">
+<sect1 id="ltree" xreflabel="ltree">
  <title>ltree</title>
 
  <indexterm zone="ltree">

doc/src/sgml/oid2name.sgml

 <!-- doc/src/sgml/oid2name.sgml -->
 
-<sect1 id="oid2name">
+<sect1 id="oid2name" xreflabel="oid2name">
  <title>oid2name</title>
 
  <indexterm zone="oid2name">

doc/src/sgml/pageinspect.sgml

 <!-- doc/src/sgml/pageinspect.sgml -->
 
-<sect1 id="pageinspect">
+<sect1 id="pageinspect" xreflabel="pageinspect">
  <title>pageinspect</title>
 
  <indexterm zone="pageinspect">

doc/src/sgml/passwordcheck.sgml

 <!-- doc/src/sgml/passwordcheck.sgml -->
 
-<sect1 id="passwordcheck">
+<sect1 id="passwordcheck" xreflabel="passwordcheck">
  <title>passwordcheck</title>
 
  <indexterm zone="passwordcheck">

doc/src/sgml/pgarchivecleanup.sgml

 <!-- doc/src/sgml/pgarchivecleanup.sgml -->
 
-<sect1 id="pgarchivecleanup">
+<sect1 id="pgarchivecleanup" xreflabel="pg_archivecleanup">
  <title>pg_archivecleanup</title>
 
  <indexterm zone="pgarchivecleanup">

doc/src/sgml/pgbench.sgml

 <!-- doc/src/sgml/pgbench.sgml -->
 
-<sect1 id="pgbench">
+<sect1 id="pgbench" xreflabel="pgbench">
  <title>pgbench</title>
 
  <indexterm zone="pgbench">

doc/src/sgml/pgbuffercache.sgml

 <!-- doc/src/sgml/pgbuffercache.sgml -->
 
-<sect1 id="pgbuffercache">
+<sect1 id="pgbuffercache" xreflabel="pg_buffercache">
  <title>pg_buffercache</title>
 
  <indexterm zone="pgbuffercache">

doc/src/sgml/pgcrypto.sgml

 <!-- doc/src/sgml/pgcrypto.sgml -->
 
-<sect1 id="pgcrypto">
+<sect1 id="pgcrypto" xreflabel="pgcrypto">
  <title>pgcrypto</title>
 
  <indexterm zone="pgcrypto">

doc/src/sgml/pgfreespacemap.sgml

 <!-- doc/src/sgml/pgfreespacemap.sgml -->
 
-<sect1 id="pgfreespacemap">
+<sect1 id="pgfreespacemap" xreflabel="pg_freespacemap">
  <title>pg_freespacemap</title>
 
  <indexterm zone="pgfreespacemap">

doc/src/sgml/pgrowlocks.sgml

 <!-- doc/src/sgml/pgrowlocks.sgml -->
 
-<sect1 id="pgrowlocks">
+<sect1 id="pgrowlocks" xreflabel="pgrowlocks">
  <title>pgrowlocks</title>
 
  <indexterm zone="pgrowlocks">

doc/src/sgml/pgstandby.sgml

 <!-- doc/src/sgml/pgstandby.sgml -->
 
-<sect1 id="pgstandby">
+<sect1 id="pgstandby" xreflabel="pg_standby">
  <title>pg_standby</title>
 
  <indexterm zone="pgstandby">

doc/src/sgml/pgstatstatements.sgml

 <!-- doc/src/sgml/pgstatstatements.sgml -->
 
-<sect1 id="pgstatstatements">
+<sect1 id="pgstatstatements" xreflabel="pg_stat_statements">
  <title>pg_stat_statements</title>
 
  <indexterm zone="pgstatstatements">

doc/src/sgml/pgstattuple.sgml

 <!-- doc/src/sgml/pgstattuple.sgml -->
 
-<sect1 id="pgstattuple">
+<sect1 id="pgstattuple" xreflabel="pgstattuple">
  <title>pgstattuple</title>
 
  <indexterm zone="pgstattuple">

doc/src/sgml/pgtestfsync.sgml

 <!-- doc/src/sgml/pgtestfsync.sgml -->
 
-<sect1 id="pgtestfsync">
+<sect1 id="pgtestfsync" xreflabel="pg_test_fsync">
  <title>pg_test_fsync</title>
 
  <indexterm zone="pgtestfsync">

doc/src/sgml/pgtrgm.sgml

 <!-- doc/src/sgml/pgtrgm.sgml -->
 
-<sect1 id="pgtrgm">
+<sect1 id="pgtrgm" xreflabel="pg_trgm">
  <title>pg_trgm</title>
 
  <indexterm zone="pgtrgm">

doc/src/sgml/pgupgrade.sgml

 <!-- doc/src/sgml/pgupgrade.sgml -->
 
-<sect1 id="pgupgrade">
+<sect1 id="pgupgrade" xreflabel="pg_upgrade">
  <title>pg_upgrade</title>
 
  <indexterm zone="pgupgrade">

doc/src/sgml/seg.sgml

 <!-- doc/src/sgml/seg.sgml -->
 
-<sect1 id="seg">
+<sect1 id="seg" xreflabel="seg">
  <title>seg</title>
 
  <indexterm zone="seg">

doc/src/sgml/sepgsql.sgml

 <!-- doc/src/sgml/sepgsql.sgml -->
 
-<sect1 id="sepgsql">
+<sect1 id="sepgsql" xreflabel="sepgsql">
  <title>sepgsql</title>
 
  <indexterm zone="sepgsql">

doc/src/sgml/sslinfo.sgml

 <!-- doc/src/sgml/sslinfo.sgml -->
 
-<sect1 id="sslinfo">
+<sect1 id="sslinfo" xreflabel="sslinfo">
  <title>sslinfo</title>
 
  <indexterm zone="sslinfo">

doc/src/sgml/tablefunc.sgml

 <!-- doc/src/sgml/tablefunc.sgml -->
 
-<sect1 id="tablefunc">
+<sect1 id="tablefunc" xreflabel="tablefunc">
  <title>tablefunc</title>
 
  <indexterm zone="tablefunc">

doc/src/sgml/test-parser.sgml

 <!-- doc/src/sgml/test-parser.sgml -->
 
-<sect1 id="test-parser">
+<sect1 id="test-parser" xreflabel="test_parser">
  <title>test_parser</title>
 
  <indexterm zone="test-parser">

doc/src/sgml/tsearch2.sgml

 <!-- doc/src/sgml/tsearch2.sgml -->
 
-<sect1 id="tsearch2">
+<sect1 id="tsearch2" xreflabel="tsearch2">
  <title>tsearch2</title>
 
  <indexterm zone="tsearch2">

doc/src/sgml/unaccent.sgml

 <!-- doc/src/sgml/unaccent.sgml -->
 
-<sect1 id="unaccent">
+<sect1 id="unaccent" xreflabel="unaccent">
  <title>unaccent</title>
 
  <indexterm zone="unaccent">

doc/src/sgml/uuid-ossp.sgml

 <!-- doc/src/sgml/uuid-ossp.sgml -->
 
-<sect1 id="uuid-ossp">
+<sect1 id="uuid-ossp" xreflabel="uuid-ossp">
  <title>uuid-ossp</title>
 
  <indexterm zone="uuid-ossp">

doc/src/sgml/vacuumlo.sgml

 <!-- doc/src/sgml/vacuumlo.sgml -->
 
-<sect1 id="vacuumlo">
+<sect1 id="vacuumlo" xreflabel="vacuumlo">
  <title>vacuumlo</title>
 
  <indexterm zone="vacuumlo">

doc/src/sgml/xml2.sgml

 <!-- doc/src/sgml/xml2.sgml -->
 
-<sect1 id="xml2">
+<sect1 id="xml2" xreflabel="xml2">
  <title>xml2</title>
 
  <indexterm zone="xml2">