📝 Note that the last link is broken in README

Said link used to lead to the discussion explaining why things are
the way they are.

README.md

@@ -57,4 +57,5 @@ heroku buildpacks:add --index 1 https://github.com/ianpurvis/heroku-buildpack-ve
   For a mysterious reason, [sometimes GitHub attaches a list of PRs to the events but sometimes that list is empty
   `[complain here]`](
   https://github.community/t5/GitHub-API-Development-and/BUG-Sometimes-rerequested-check-run-events-don-t-contain-a-PR/m-p/26964/thread-id/2189
-  )
+  ). The link is historic and the discussion contents seem to have been
+  lost during GitHub's platform migrations.