[clang-tools-extra] Update clang tidy Contributing guide (PR #106672)

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MichelleCDjunaidi wrote:

Hmm, in that case, would it be better to note the Windows exception in the documentation and open up an issue tracker for the tab issue instead, since the bug and fix (due to it affecting all tab-related operations on Windows) is out of scope for this documentation PR?

Also, what's the workflow for adding to a merger PR? Just make a new PR, correct?

https://github.com/llvm/llvm-project/pull/106672