Fix pluralization errors in various files

* Replaced instances of 'return an' with 'returns an'
* fixed pluralization errors

discord/guild.py

@@ -1458,7 +1458,7 @@ class Guild(Hashable):
         return state.http.ack_guild(self.id)
 
     def audit_logs(self, *, limit=100, before=None, after=None, oldest_first=None, user=None, action=None):
-        """Return an :class:`AsyncIterator` that enables receiving the guild's audit logs.
+        """Returns an :class:`AsyncIterator` that enables receiving the guild's audit logs.
 
         You must have the :attr:`~Permissions.view_audit_log` permission to use this.