doc: Fix up title case

This fixes some instances that were missed in earlier processings and
that now look a bit strange because they are inconsistent with nearby
titles.

Author: petere

doc/src/sgml/dml.sgml

@@ -262,7 +262,7 @@ DELETE FROM products;
  </sect1>
 
  <sect1 id="dml-returning">
-  <title>Returning Data From Modified Rows</title>
+  <title>Returning Data from Modified Rows</title>
 
   <indexterm zone="dml-returning">
    <primary>RETURNING</primary>

doc/src/sgml/func.sgml

@@ -6849,7 +6849,7 @@ SELECT regexp_match('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
 <!-- end re_syntax.n man page -->
 
    <sect3 id="posix-vs-xquery">
-   <title>Differences From XQuery (<literal>LIKE_REGEX</literal>)</title>
+   <title>Differences from XQuery (<literal>LIKE_REGEX</literal>)</title>
 
    <indexterm zone="posix-vs-xquery">
     <primary><literal>LIKE_REGEX</literal></primary>

doc/src/sgml/plpgsql.sgml

@@ -1657,7 +1657,7 @@ END;
    </para>
 
    <sect2 id="plpgsql-statements-returning">
-    <title>Returning From a Function</title>
+    <title>Returning from a Function</title>
 
     <para>
      There are two commands available that allow you to return data