Make an editorial pass over the newly SGML-ified contrib documentation.

Fix lots of bad markup, bad English, bad explanations.

This commit covers only about half the contrib modules, but I grow weary...

doc/src/sgml/btree-gist.sgml

@@ -1,37 +1,56 @@
+<!-- $PostgreSQL: pgsql/doc/src/sgml/btree-gist.sgml,v 1.4 2007/12/06 04:12:09 tgl Exp $ -->
+
 <sect1 id="btree-gist">
  <title>btree_gist</title>
- 
+
  <indexterm zone="btree-gist">
   <primary>btree_gist</primary>
  </indexterm>
 
  <para>
-  btree_gist is a B-Tree implementation using GiST that supports the int2, int4,
-  int8, float4, float8 timestamp with/without time zone, time
-  with/without time zone, date, interval, oid, money, macaddr, char,
-  varchar/text, bytea, numeric, bit, varbit and inet/cidr types.
+  <filename>btree_gist</> provides sample GiST operator classes that
+  implement B-Tree equivalent behavior for the data types
+  <type>int2</>, <type>int4</>, <type>int8</>, <type>float4</>,
+  <type>float8</>, <type>numeric</>, <type>timestamp with time zone</>,
+  <type>timestamp without time zone</>, <type>time with time zone</>,
+  <type>time without time zone</>, <type>date</>, <type>interval</>,
+  <type>oid</>, <type>money</>, <type>char</>,
+  <type>varchar</>, <type>text</>, <type>bytea</>, <type>bit</>,
+  <type>varbit</>, <type>macaddr</>, <type>inet</>, and <type>cidr</>.
+ </para>
+
+ <para>
+  In general, these operator classes will not outperform the equivalent
+  standard btree index methods, and they lack one major feature of the
+  standard btree code: the ability to enforce uniqueness.  However,
+  they are useful for GiST testing and as a base for developing other
+  GiST operator classes.
  </para>
 
  <sect2>
   <title>Example usage</title>
-  <programlisting>
-   CREATE TABLE test (a int4);
-   -- create index
-   CREATE INDEX testidx ON test USING gist (a);
-   -- query
-   SELECT * FROM test WHERE a &lt; 10;
-  </programlisting>
+
+<programlisting>
+CREATE TABLE test (a int4);
+-- create index
+CREATE INDEX testidx ON test USING gist (a);
+-- query
+SELECT * FROM test WHERE a &lt; 10;
+</programlisting>
+
  </sect2>
- 
+
  <sect2>
   <title>Authors</title>
+
   <para>
-   All work was done by Teodor Sigaev (<email>teodor@stack.net</email>) , 
-   Oleg Bartunov (<email>oleg@sai.msu.su</email>), Janko Richter 
-   (<email>jankorichter@yahoo.de</email>).  See 
-   <ulink url="http://www.sai.msu.su/~megera/postgres/gist"></ulink> for additional 
-   information.
+   Teodor Sigaev (<email>teodor@stack.net</email>) ,
+   Oleg Bartunov (<email>oleg@sai.msu.su</email>), and
+   Janko Richter (<email>jankorichter@yahoo.de</email>).  See
+   <ulink url="http://www.sai.msu.su/~megera/postgres/gist"></ulink>
+   for additional information.
   </para>
+
  </sect2>
 
 </sect1>