[llvm] [GitHub] Add review instructions for commit access requests (PR #168971)

[Baranov Victor via llvm-commits]

================
@@ -526,7 +526,10 @@ Most commonly these reviewers will provide the necessary approval, but approvals
 from other LLVM committers are also acceptable. Those reviewing the application are
 confirming that you have indeed had three patches committed, and that based on interactions
 on those reviews and elsewhere in the LLVM community they have no concern about you
-adhering to our Developer Policy and Code of Conduct.
+adhering to our Developer Policy and Code of Conduct. Reviewers should clearly state their
+reasoning for accepting or rejecting the request, and finish with a clear statement such
+as "I approve of this request" or "I do not approve of this request".
----------------
vbvictor wrote:

```suggestion
adhering to our Developer Policy and Code of Conduct. Reviewers should clearly state their
reasoning for accepting or rejecting the request, and finish with a clear statement such
as "I approve of this request" ("LGTM") or "I do not approve of this request".
```

Seems to me that 99% of people typically write LGTM so I think we can state it as an available option that we all familiar to.

https://github.com/llvm/llvm-project/pull/168971