Adjust user-facing documentation to explain why we don't check pgpass

file permissions on Windows.

doc/src/sgml/libpq.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.232 2007/02/19 22:06:23 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.233 2007/02/20 17:47:04 tgl Exp $ -->
 
  <chapter id="libpq">
   <title><application>libpq</application> - C Library</title>
@@ -4337,12 +4337,12 @@ default socket directory) connections coming from the local machine.
 </para>
 
 <para>
-The permissions on <filename>.pgpass</filename> must disallow any
-access to world or group; achieve this by the command
+On Unix systems, the permissions on <filename>.pgpass</filename> must disallow
+any access to world or group; achieve this by the command
 <command>chmod 0600 ~/.pgpass</command>.
 If the permissions are less strict than this, the file will be ignored.
-(The file permissions are not currently checked on Microsoft Windows,
-however.)
+On Microsoft Windows, the file is stored in a directory that is secure by
+default, so no special permissions check is made.
 </para>
 </sect1>