Doc: add guidance on taking over a stale pull request

[Aniketsy]

Fixes #13860

What does this implement/fix?

Additional information

[Aniketsy]

I think we don't need changelog entry for this, please let me know if this needs further improvements. (i'll fix these ci failures)
thanks!

[tsbinns]

Hey @Aniketsy, thanks for the PR.
Have got some small comments below, with some bigger things that @drammock can hopefully weigh in on.

[Aniketsy]

@tsbinns thanks ❤️ for the review and the pointer, it make sense, to add some more details, i'll address these review points tomorrow, as its here approx 1 am ...

[tsbinns]

Hi @Aniketsy. The outstanding questions have now been resolved. Do you want to address the remaining points? If it helps, I can also push some commits.

[Aniketsy]

Hi @Aniketsy. The outstanding questions have now been resolved. Do you want to address the remaining points? If it helps, I can also push some commits.

I've pushed some changes, please feel free to push some commits or I can also address these ci fails and review points, but i may take some time. Thanks!

[tsbinns]

Just pushed some changes. Let's also see if the errors are resolved.