Clarify use of MD5 authentication and pg_shadow encryption.

doc/src/sgml/client-auth.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.74 2005/04/09 03:52:43 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.75 2005/04/21 22:19:19 momjian Exp $
 -->
 
 <chapter id="client-authentication">
@@ -575,8 +575,8 @@ local   db1,db2,@demodbs  all                         md5
     The password-based authentication methods are <literal>md5</>,
     <literal>crypt</>, and <literal>password</>. These methods operate
     similarly except for the way that the password is sent across the
-    connection.  But only <literal>md5</> supports encrypted
-    passwords stored in <structname>pg_shadow</structname>;
+    connection.  However, only <literal>md5</> allows encrypted
+    passwords to be stored in <structname>pg_shadow</structname>;
     the other two require unencrypted passwords to be stored there.
    </para>