[llvm] [docs] Update docs on code-review process (PR #111735)

[Nikita Popov via llvm-commits]

https://github.com/nikic requested changes to this pull request.

This document is just an overview, we have detailed documentation of the code review policy in https://llvm.org/docs/CodeReview.html, which is also already linked. 

In particular, https://llvm.org/docs/CodeReview.html#lgtm-how-a-patch-is-accepted explains that it is the responsibility of the approving reviewer to consider other feedback on the patch and indicate if their approval is conditional.

https://github.com/llvm/llvm-project/pull/111735