Fix documentation error: GRANT/REVOKE for roles only accept role names

as grantees, not PUBLIC ... and you can't say GROUP either.  Noted by
Brian Hurt.

doc/src/sgml/ref/grant.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/grant.sgml,v 1.59 2006/07/20 18:00:03 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/grant.sgml,v 1.60 2006/08/02 16:29:49 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -50,8 +50,7 @@ GRANT { CREATE | ALL [ PRIVILEGES ] }
     ON TABLESPACE <replaceable>tablespacename</> [, ...]
     TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
 
-GRANT <replaceable class="PARAMETER">role</replaceable> [, ...]
-    TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...] [ WITH ADMIN OPTION ]
+GRANT <replaceable class="PARAMETER">role</replaceable> [, ...] TO <replaceable class="PARAMETER">username</replaceable> [, ...] [ WITH ADMIN OPTION ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -325,6 +324,12 @@ GRANT <replaceable class="PARAMETER">role</replaceable> [, ...]
    Roles having <literal>CREATEROLE</> privilege can grant or revoke
    membership in any role that is not a superuser.
   </para>
+
+  <para>
+   Unlike the case with privileges, membership in a role cannot be granted
+   to <literal>PUBLIC</>.  Note also that this form of the command does not
+   allow the noise word <literal>GROUP</>.
+  </para>
  </refsect2>
  </refsect1>
 

doc/src/sgml/ref/revoke.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/revoke.sgml,v 1.38 2006/04/30 21:15:33 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/revoke.sgml,v 1.39 2006/08/02 16:29:49 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -65,8 +65,7 @@ REVOKE [ GRANT OPTION FOR ]
     [ CASCADE | RESTRICT ]
 
 REVOKE [ ADMIN OPTION FOR ]
-    <replaceable class="PARAMETER">role</replaceable> [, ...]
-    FROM { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
+    <replaceable class="PARAMETER">role</replaceable> [, ...] FROM <replaceable class="PARAMETER">username</replaceable> [, ...]
     [ CASCADE | RESTRICT ]
 </synopsis>
  </refsynopsisdiv>
@@ -119,6 +118,8 @@ REVOKE [ ADMIN OPTION FOR ]
   <para>
    When revoking membership in a role, <literal>GRANT OPTION</> is instead
    called <literal>ADMIN OPTION</>, but the behavior is similar.
+   Note also that this form of the command does not
+   allow the noise word <literal>GROUP</>.
   </para>
  </refsect1>
 

doc/src/sgml/user-manag.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/user-manag.sgml,v 1.35 2006/04/30 21:15:32 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/user-manag.sgml,v 1.36 2006/08/02 16:29:49 tgl Exp $ -->
 
 <chapter id="user-manag">
  <title>Database Roles and Privileges</title>
@@ -375,7 +375,9 @@ REVOKE <replaceable>group_role</replaceable> FROM <replaceable>role1</replaceabl
 </synopsis>
    You can grant membership to other group roles, too (since there isn't
    really any distinction between group roles and non-group roles).  The
-   only restriction is that you can't set up circular membership loops.
+   database will not let you set up circular membership loops.  Also,
+   it is not permitted to grant membership in a role to
+   <literal>PUBLIC</literal>.
   </para>
 
   <para>