DOC: clearified admin permissions

src/doc/permissions.rst

@@ -108,16 +108,16 @@ Administration permissions
 
 There is one special permission rule that grants global administration
 permissions to a user or a role: ``Grant(*)P``, i.e., grant everything with
-priority. This promotes the user or group to administration level, very similar
-to the ``root`` user on POSIX systems, and no other rule can deny any permission
-from this user or role. Thus the ``Grant(*)P`` permission should really only be
-used for administration users and in no other case. So, ...
+priority. This promotes a user with this role to administration level, very
+similar to the ``root`` user on POSIX systems. As with any other rule, the
+effect of this rule can be overriden by *Deny* rules with priority. The
+``Grant(*)P`` permission should really only be used for administration users
+and in no other case.
 
 .. warning::
 
-   The ``Grant(*)P`` administration permission cannot be overruled by any other
-   permission rule. Be cautious when assigning administration privileges to
-   users and roles.
+   ``Grant(*)P`` is a powerful administration permission rule. Be cautious
+   when assigning administration privileges to users and roles.
 
 
 How to set permissions