The page says:
You can link a pull request to an issue by using a supported keyword in the pull request’s description.
But when I have forked a repository, and am trying to connect a pull request to an issue in the ORIGINAL REPOSITORY, what the hell am I supposed to do?
Who determines which of these keywords is appropriate?!?!?!
Do I just freeform sprinkle this keyword/issue number anywhere in the text of the pull request comment? This is inappropriately vague.