docs: update website

README.md

@@ -22,7 +22,7 @@ See also: [Socket.IO-client Java](https://github.com/socketio/socket.io-client-j
 | -------------- | ---------------- | ---------------- |
 | 0.9.x  | 1.x | 1.x |
 | 1.x    | 3.x | 2.x |
-| -      | 4.x | 3.x |
+| WIP    | 4.x | 3.x |
 
 ## Installation
 The latest artifact is available on Maven Central.
@@ -132,43 +132,6 @@ socket = new Socket(opts);
 ## Features
 This library supports all of the features the JS client does, including events, options and upgrading transport. Android is fully supported.
 
-### Extra features only for Java client
-
-#### Accessing HTTP Headers
-You can access HTTP headers like the following.
-
-```java
-socket.on(Socket.EVENT_TRANSPORT, new Emitter.listener() {
-  @Override
-  public void call(Object... args) {
-    // Called on a new transport created.
-    Transport transport = (Transport)args[0];
-
-    transport.on(Transport.EVENT_REQUEST_HEADERS, new Emitter.Listener() {
-      @Override
-      public void call(Object... args) {
-        @SuppressWarnings("unchecked")
-        Map<String, List<String>> headers = (Map<String, List<String>>)args[0];
-        // send cookie value to server.
-        headers.put("Cookie", Arrays.asList("foo=1;"));
-      }
-    }).on(Transport.EVENT_RESPONSE_HEADERS, new Emitter.Listener() {
-      @Override
-      public void call(Object... args) {
-        @SuppressWarnings("unchecked")
-        Map<String, List<String>> headers = (Map<String, List<String>>)args[0];
-        // receive cookie value from server.
-        String cookie = headers.get("Set-Cookie").get(0);
-      }
-    });
-  }
-});
-```
-
-See the Javadoc for more details.
-
-http://socketio.github.io/engine.io-client-java/apidocs/
-
 ## License
 
 MIT