Diviner: Contributing Code: Remove outdated sentences
Summary: GitHub nowadays allows disabling Pull Requests, and it looks like they are already disabled for projects under the phorgeit organization on GitHub.
Test Plan:
* Read https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/enabling-features-for-your-repository/disabling-pull-requests
* Find the Backspace key to delete a sentence in the docs
Reviewers: O1 Blessed Committers, mainframe98
Reviewed By: O1 Blessed Committers, mainframe98
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D26802