doc: adjust time zone names text

Reported-by: Kevin <kcolagio@gmail.com>

Discussion: https://postgr.es/m/154082462281.30897.14043119084654378035@wrigleys.postgresql.org

Backpatch-through: 9.4

Author: bmomjian

doc/src/sgml/datatype.sgml

@@ -2419,7 +2419,7 @@ January 8 04:05:06 1999 PST
         linkend="view-pg-timezone-names"/>).
         <productname>PostgreSQL</productname> uses the widely-used IANA
         time zone data for this purpose, so the same time zone
-        names are also recognized by much other software.
+        names are also recognized other software.
        </para>
       </listitem>
       <listitem>