[docs] Document remoteDisconnect method (#179)

Author: overflowz

README.md

@@ -110,6 +110,17 @@ io.adapter.remoteLeave('<my-id>', 'room1', function (err) {
 });
 ```
 
+### RedisAdapter#remoteDisconnect(id:String, close:Boolean, fn:Function)
+
+Makes the socket with the given id to get disconnected. If `close` is set to true, it also closes the underlying socket. The callback will be called once the socket was disconnected, or with an `err` argument if the socket was not found.
+
+```js
+io.adapter.remoteDisconnect('<my-id>', true, function (err) {
+  if (err) { /* unknown id */ }
+  // success
+});
+```
+
 ### RedisAdapter#customRequest(data:Object, fn:Function)
 
 Sends a request to every nodes, that will respond through the `customHook` method.