docs(contributing): clarify pull request review guidelines

[HonkingGoose]

Changes:

• Explain how to apply reviewer suggested changes (and how to batch them, to reduce noise!)
• Explain how to resolve a review comment (instead of commenting "done")
• Link to relevant GitHub Docs for both concepts

Context:

As asked for by @viceice in #13463 (comment):

So we only need some sentence about to suppress short comments like Done and instead resolve conversation.

I see that contributors sometimes do not use the maintainer provided code suggestions. It might be good to mention the "apply changes" workflow here as well, to nudge people into using the suggestion as-is, instead of duplicating the work, and then commenting "done", and leaving us to manually resolve the related items.

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please tick one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[renovate-release]

🎉 This PR is included in version 31.25.0 🎉

The release is available on:

• GitHub release
• 31.25.0

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