9.5 release notes: mention lack of char() sort improvements

Report by Peter Geoghegan

Backpatch through 9.5

doc/src/sgml/datatype.sgml

@@ -1139,7 +1139,8 @@ SELECT '52093.89'::money::numeric::float8;
      advantages in some other database systems, there is no such advantage in
      <productname>PostgreSQL</productname>; in fact
      <type>character(<replaceable>n</>)</type> is usually the slowest of
-     the three because of its additional storage costs.  In most situations
+     the three because of its additional storage costs and slower
+     sorting.  In most situations
      <type>text</type> or <type>character varying</type> should be used
      instead.
     </para>