[clang-tools-extra] [doc] Add documentation for clang-change-namespace (PR #148277)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> @AaronBallman @tJener I've addressed all of you comments and hope this PR is now good to merge. Could you give it one last review? Am I supposed to mark the discussions we had as Resolved or is that up to you?

I gave it a review and my LG, but let's wait a bit for @tJener to weigh in before landing.

As for marking discussions resolved, I usually let the person who left the original comment decide if it's resolved or not, but others mark things resolved when they think they've addressed all the feedback, so it's not consistent. :-)

https://github.com/llvm/llvm-project/pull/148277