Renamed events in GroupManager

doc/ConnectionGroups.md

@@ -36,6 +36,14 @@ $groupManager->on('created', function (ConnectionGroup $group) {
 $middleware = new WebSocketMiddleware($groupManager);
 ```
 
+## Sending messages
+
+You can use the `ConnectionGoup::writeAll(string $payload)` method to send the payload to all members of the group.
+
+## Disconnecting clients
+
+You can disconnect clients cleanly on shutdown by using the `GroupManager::closeAll(string $reason, int $code)` method. You can also call on `ConnectionGrroup::closeAll` manually do disconnect a whole group.
+
 ## Future
 
 * Add a GroupManagerImplementation so custom logic can be provided.