Fix markup tag error, envvar -> envar.

doc/src/sgml/charset.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/charset.sgml,v 2.89 2008/09/23 10:58:03 heikki Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/charset.sgml,v 2.90 2008/09/24 16:30:26 momjian Exp $ -->
 
 <chapter id="charset">
  <title>Localization</>
@@ -321,7 +321,7 @@ initdb --locale=sv_SE
   <para>
    An important restriction, however, is that each database's character set
    must be compatible with the database's <envar>LC_CTYPE</> and
-   <envvar>LC_COLLATE</> locale settings. For <literal>C</> or
+   <envar>LC_COLLATE</> locale settings. For <literal>C</> or
    <literal>POSIX</> locale, any character set is allowed, but for other
    locales there is only one character set that will work correctly.
   </para>