update to v4 (#20392)

Author: minggo

CHANGELOG

@@ -1,4 +1,4 @@
-cocos2d-x-4.0  ??
+cocos2d-x-4.0  Dec.3 2019
 
 [HIGHLIGHT]     Support metal
 [HIGHLIGHT]     Use CMake for all platforms

README.md

@@ -6,12 +6,12 @@ cocos2d-x
 
 |Win32|Others|
 | ----|------|
-[![Build status](https://ci.appveyor.com/api/projects/status/nlgirox464j6ldg5/branch/v3?svg=true)](https://ci.appveyor.com/project/minggo/cocos2d-x/branch/v3)|[![Build Status](https://travis-ci.org/cocos2d/cocos2d-x.svg?branch=v3)](https://travis-ci.org/cocos2d/cocos2d-x)
+[![Build status](https://ci.appveyor.com/api/projects/status/nlgirox464j6ldg5/branch/v4?svg=true)](https://ci.appveyor.com/project/minggo/cocos2d-x/branch/v4)|[![Build Status](https://travis-ci.org/cocos2d/cocos2d-x.svg?branch=v4)](https://travis-ci.org/cocos2d/cocos2d-x)
 
 
 [cocos2d-x][1] is a multi-platform framework for building 2d games, interactive books, demos and other graphical applications.
 It is based on [cocos2d-iphone][2], but instead of using Objective-C, it uses C++.
-It works on iOS, Android, OS X, Windows and Linux.
+It works on iOS, Android, macOS, Windows and Linux.
 
 **Cocos2d-x Framework Architecture**:
 
@@ -50,8 +50,8 @@ Documentations and samples
 * [All Docs in a single place!](http://cocos2d-x.org/docs/)
 * [Online API Reference](http://cocos2d-x.org/docs/api-ref/index.html) _Note that Cocos2d-x and Cocos Creator have different API set_
 * [Programmers Guide](http://cocos2d-x.org/docs/programmers-guide/2/index.html)
-* [Latest Release Note](https://github.com/cocos2d/cocos2d-x/blob/v3/docs/RELEASE_NOTES.md)
-* [Changelog](https://github.com/cocos2d/cocos2d-x/blob/v3/CHANGELOG)
+* [Latest Release Note](https://github.com/cocos2d/cocos2d-x/blob/v4/docs/RELEASE_NOTES.md)
+* [Changelog](https://github.com/cocos2d/cocos2d-x/blob/v4/CHANGELOG)
 
 Main features
 -------------
@@ -161,7 +161,6 @@ Learning Resources
 * [Android Fundamentals](https://developer.android.com/guide/components/fundamentals.html)
 * [Make School Tutorials](https://www.makeschool.com/tutorials/)
 * [Games From Scratch](http://www.gamefromscratch.com/page/Cocos2d-x-CPP-Game-Programming-Tutorial-Series.aspx)
-* [Cocos2d sample games](https://github.com/cocos2d/cocos2d-x-samples)
 
 Spreading the word!
 --------------------------------
@@ -172,21 +171,15 @@ You can help us spread the word about cocos2d-x! We would surely appreciate it!
 * Read our [Blog](http://blog.cocos2d-x.org/) and promote it on your social media.
 * Become a [Regional Coordinator](http://discuss.cocos2d-x.org/t/we-need-regional-coordinators/24104)
 
-See what we are planning!
---------------------------------
-You can see exactly what we are planning to do with the Cocos family of products.
-
-* [Cocos2d-x roadmap](https://trello.com/b/Np6obnuE/cocos2d-x-roadmap)
-
 Where to get help
 --------------------------------
 
 * [English Forums](http://discuss.cocos2d-x.org)
 * [中文社区](http://forum.cocos.com/c/cocos2d-x)
 * [Bug Tracker](https://github.com/cocos2d/cocos2d-x/issues)
 * [API Reference](http://cocos2d-x.org/docs/api-ref/index.html).
-* [Latest Release Note](https://github.com/cocos2d/cocos2d-x/blob/v3/docs/RELEASE_NOTES.md)
-* [Changelog](https://github.com/cocos2d/cocos2d-x/blob/v3/CHANGELOG)
+* [Latest Release Note](https://github.com/cocos2d/cocos2d-x/blob/v4/docs/RELEASE_NOTES.md)
+* [Changelog](https://github.com/cocos2d/cocos2d-x/blob/v4/CHANGELOG)
 * IRC. We are in [Freenode](https://webchat.freenode.net/) in the _#cocos2d_ channel
 * `cpp-tests` project. This project is our basis for testing. Use this project to
 learn how we implement the functionality of the engine. This project is located in