Update readme & add wechat code

[liuxiaocs7]

• fix email
• add weixin pic

[zyxxoo]

Need update soon~ refer

[liuxiaocs7]

Hi, @imbajin and @zyxxoo, how do you think it is now, is there anything that needs to be improved?

[imbajin]

Also found outdated message in https://hugegraph.apache.org/docs/introduction/readme/ (EN & CN), could add a task in task lists for others to take

And also for the README update for computer & server