Update community forum link in README

Add QQ group link to community forum entry.

Author: Sunrisepeak

profile/README.md

@@ -80,7 +80,7 @@ auto main() -> int {
 ### 相关链接
 
 - [社区官网](https://mcpp.d2learn.org)
-- [社区论坛](https://forum.d2learn.org/category/20)
+- [社区论坛](https://forum.d2learn.org/category/20) ([`Q: 1067245099`](https://qm.qq.com/q/nBQdBaYNna))
 - [社区公开任务发布面板](https://github.com/orgs/mcpp-community/projects/3)
 - [mcpplibs | 现代C++库](https://github.com/mcpplibs)
 - [mcpp社区成员和开发者 | 申请入口](https://github.com/mcpp-community/members)