Rewrite sentence in "Allowing changes to a pull request branch created from a fork"

[HonkingGoose]

Code of Conduct

• I have read and agree to the GitHub Docs project's Code of Conduct

What article on docs.github.com is affected?

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork

What part(s) of the article would you like to see updated?

This sentence is hard to understand. It's too long and tries to explain three things at once:

Only pull request authors can give upstream repository maintainers, or those with push access to the upstream repository, permission to make commits to their pull request's compare branch in a user-owned fork.

This one sentence mentions:

• Only pull request authors can give permission
• Lists who can commit: upstream maintainers / those with push access to upstream
• That the branch needs to be on a user-owned fork

This sentence needs a rewrite.

Additional information

Trying one more time to get this past your @docubot:

• Rewrite sentence #23020

[cmwilson21]

👋 @HonkingGoose - Sorry about docubot, it doesn't like short titles (two words or less) as those tend to be spammy. We appreciate you changing up the title and opening again!

I'll get this triaged for review! ⚡