Updated guidance with exemption for C++ extensions

[leslierichardson95]

No description provided.

[PRMerger12]

Microsoft authors of articles need to make updates through the private repository so the updates can be staged and validated by the current validation rules. After you review staging and fix all validation issues, you can add the sign-off comment to let the PR reviewers know the updates are ready to be merged.It's easy to access the private repo version of your articles in GitHub. Just add -pr to the URL, as follows:
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We have closed this pull request. Please resubmit the updates through the private repo. For more information, [see the contributor guide].(https://docs.microsoft.com/en-us/contribute/)