Doc: adjust documentation related to index support functions.

Commit 15cb2bd2 neglected to make the running text match the
tables, leaving the reader with the strong impression that
we cannot count.  Also, don't drop an unrelated para between
a table and the para describing it.

doc/src/sgml/xindex.sgml

@@ -400,22 +400,22 @@
    specified by the index method.
   </para>
 
+  <para>
+   Additionally, some opclasses allow users to specify parameters which
+   control their behavior.  Each builtin index access method has an optional
+   <function>options</function> support function, which defines a set of
+   opclass-specific parameters.
+  </para>
+
   <para>
    B-trees require a comparison support function,
-   and allow three additional support functions to be
+   and allow four additional support functions to be
    supplied at the operator class author's option, as shown in <xref
    linkend="xindex-btree-support-table"/>.
    The requirements for these support functions are explained further in
    <xref linkend="btree-support-funcs"/>.
   </para>
 
-  <para>
-   Additionally, some opclasses allow users to specify parameters which
-   control their behavior.  Each builtin index access method has an optional
-   <function>options</function> support function, which defines a set of
-   opclass-specific parameters.
-  </para>
-
    <table tocentry="1" id="xindex-btree-support-table">
     <title>B-Tree Support Functions</title>
     <tgroup cols="2">
@@ -469,8 +469,8 @@
    </table>
 
   <para>
-   Hash indexes require one support function, and allow a second one to be
-   supplied at the operator class author's option, as shown in <xref
+   Hash indexes require one support function, and allow two additional ones to
+   be supplied at the operator class author's option, as shown in <xref
    linkend="xindex-hash-support-table"/>.
   </para>
 
@@ -511,7 +511,7 @@
    </table>
 
   <para>
-   GiST indexes have nine support functions, two of which are optional,
+   GiST indexes have ten support functions, three of which are optional,
    as shown in <xref linkend="xindex-gist-support-table"/>.
    (For more information see <xref linkend="gist"/>.)
   </para>
@@ -594,7 +594,7 @@
    </table>
 
   <para>
-   SP-GiST indexes require five support functions, as
+   SP-GiST indexes have six support functions, one of which is optional, as
    shown in <xref linkend="xindex-spgist-support-table"/>.
    (For more information see <xref linkend="spgist"/>.)
   </para>
@@ -653,7 +653,7 @@
    </table>
 
   <para>
-   GIN indexes have six support functions, three of which are optional,
+   GIN indexes have seven support functions, four of which are optional,
    as shown in <xref linkend="xindex-gin-support-table"/>.
    (For more information see <xref linkend="gin"/>.)
   </para>
@@ -730,9 +730,9 @@
    </table>
 
   <para>
-   BRIN indexes have four basic support functions, as shown in
-   <xref linkend="xindex-brin-support-table"/>; those basic functions
-   may require additional support functions to be provided.
+   BRIN indexes have five basic support functions, one of which is optional,
+   as shown in <xref linkend="xindex-brin-support-table"/>.  Some versions of
+   the basic functions require additional support functions to be provided.
    (For more information see <xref linkend="brin-extensibility"/>.)
   </para>