Please supply as much relevant information as possible, including:
If uncertain, bugs can always be posted to the main repository. But if you are sure a bug is in an upstream project, you can file it there:
Pull requests must (of course) go to the proper repository.
Documentation (site) bugs should be filed in the same Issue Tracker.
Include relevant information including:
The Page bug link on the bottom-right of every page opens the Issue Tracker pre-seeded with the current page URL and title.