Remove unportable use of SGML character-code entity.

It'd be nice to be able to spell Jan Urbanski's name with the correct
accent marks, but we haven't yet found a way that works in everybody's
docs toolchain.  This way definitely doesn't.

doc/src/sgml/release-9.2.sgml

@@ -1951,7 +1951,7 @@
       <listitem>
        <para>
         Add PL/Python <acronym>SPI</acronym> cursor support (Jan
-        Urba&#324;nski, Steve Singer)
+        Urbanski, Steve Singer)
        </para>
        
        <para>

doc/src/sgml/release.sgml

@@ -17,7 +17,7 @@ pg_[A-Za-z0-9_]+                <application>, <structname>
 [a-z]+_[a-z_]+                   <varname>
 
 non-ASCII characters            find using grep -P '[\x80-\xFF]'
-                                convert to HTML4 entity (&) escapes
+                                convert to HTML4 named entity (&) escapes
 
         official:      http://www.w3.org/TR/html4/sgml/entities.html
         one page:      http://www.zipcon.net/~swhite/docs/computers/browsers/entities_page.html
@@ -30,7 +30,9 @@ non-ASCII characters            find using grep -P '[\x80-\xFF]'
         does not support it
           http://www.pemberley.com/janeinfo/latin1.html#latexta
 
-        Alvaro Herrera is &Aacute;lvaro Herrera
+        do not use numeric character escapes (&#nnn;), they are not portable
+
+        Example: Alvaro Herrera is &Aacute;lvaro Herrera
 
 wrap long lines