switch master to 6.x and create a new branch for 5.x

[leizhiyuan]

Your question

1. complete all issues about 6.x branch
2. create a brach 5.x from master
3. merge 6.x to master
4. delete 6.x branch
5. change readme

Your scenes

describe your use scenes (why need this feature)

Your advice

describe the advice or solution you'd like

Environment

• Starter version:
• JVM version (e.g. java -version):
• OS version (e.g. uname -a):
• Maven version:
• IDE version: