docs: add new version convenant contribuitor guide link (#32107)

Summary:
## Summary
this PR update available link version in Contributor Covenant.!

cc: yungsters

Changelog:
[General][Changed] Updated to Contributor Covenant v2.1

Pull Request resolved: #32107

Reviewed By: lunaleaps

Differential Revision: D30616702

Pulled By: yungsters

fbshipit-source-id: b79b07cfa14154fbe948e7bb4d6698925be2cdd4

CODE_OF_CONDUCT.md

@@ -67,8 +67,8 @@ members of the project's leadership.
 
 ## Attribution
 
-This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
-available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 2.1,
+available at https://www.contributor-covenant.org/version/2/1/code_of_conduct/
 
 [homepage]: https://www.contributor-covenant.org