Merge pull request #480 from iNilo/patch-1

Add missing @error annotation to GetClientSerial

plugins/include/clients.inc

@@ -821,6 +821,7 @@ native ChangeClientTeam(client, team);
  *
  * @param client		Client index.
  * @return	Serial number.
+ * @error				Invalid client index, or client not connected.
  */
 native GetClientSerial(client);