add disconnect reason

example.js

@@ -160,7 +160,7 @@ client.on('message_revoke_me', async (msg) => {
     console.log(msg.body); // message before it was deleted.
 });
 
-client.on('disconnected', () => {
-    console.log('Client was logged out');
+client.on('disconnected', (reason) => {
+    console.log('Client was logged out', reason);
 });
 

src/Client.js

@@ -206,8 +206,9 @@ class Client extends EventEmitter {
                 /**
                  * Emitted when the client has been disconnected
                  * @event Client#disconnected
+                 * @param {WAState} reason state that caused the disconnect
                  */
-                this.emit(Events.DISCONNECTED);
+                this.emit(Events.DISCONNECTED, state);
                 this.destroy();
             }
         });