Pretty much every project that I actively maintain on my GitHub account has a change log of some description. For a long time now, whenever I add a new entry to the log, I'll include a link to the PR that implements that change. Inevitably, this results in me adding the ChangeLog entry, creating the PR, then doing a follow-up change and commit now that I know the PR number, which allows me to add the link.
So I've created next-gh-pr.el to save me just a little time and let me be just a little more lazy. Inside it I've currently got a next-gh-pr-insert-markdown-link command which, when run, as you might imagine, inserts a link to the next likely PR URL as Markdown.
Working out the next URL is simple enough: get the latest issue and PR number, take whichever is the highest, and add 1. There is the wrinkle that discussions also cause this number to bump, and getting the latest discussion number is a little extra faff that I can't be bothered with right now, but my projects very seldom have discussions taking place anyway.