Update documentation after bugzilla migration

[asl]

We need to update all documentation after bugzilla migration

• Documentation
• Website
• Error messages
• Something else

[mattmccutchen-cci]

One thing I noticed: https://bugs.llvm.org has a banner at the top that says, "LLVM Bugzilla is read-only and represents the historical archive of all LLVM issues filled before November 26, 2011." The year should be 2021.

[asl]

@mattmccutchen-cci Fixed, thanks!

[AaronBallman]

https://llvm.org/docs/BugLifeCycle.htm needs to be updated (moving this over so you don't have to find it by clicking through the mentioned bugs).

[chfast]

https://llvm.org/docs/BugLifeCycle.htm needs to be updated (moving this over so you don't have to find it by clicking through the mentioned bugs).

This has been done in f3e2294 ?