Place GiST and GIN text search indexes as secondary items under the main

"index" entries for GIN/GiST.

doc/src/sgml/textsearch.sgml

@@ -1824,11 +1824,10 @@ SHOW default_text_search_config;
       <secondary>GiST</secondary>
      </indexterm>
 
-<!--
      <indexterm zone="textsearch-indexes">
       <primary>GiST</primary>
+      <secondary>text search</secondary>
      </indexterm>
--->
      <term>
       <synopsis>
        CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable> USING gist(<replaceable>column</replaceable>);
@@ -1851,11 +1850,11 @@ SHOW default_text_search_config;
       <secondary>GIN</secondary>
      </indexterm>
 
-<!--
      <indexterm zone="textsearch-indexes">
       <primary>GIN</primary>
+      <secondary>text search</secondary>
      </indexterm>
--->
+
      <term>
       <synopsis>
        CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable> USING gin(<replaceable>column</replaceable>);