Idea: notification for link to recently closed issue

[Akuli]

This is a tooling idea that isn't really specific to Porcupine, but would be useful for Porcupine.

Consider this situation:

1. I run into a problem when developing Porcupine.
2. I don't fix it immediately. Instead, I create an issue, and add a hacky workaround for it together with a link to the issue.
3. A long time passes.
4. I fix the issue.
5. Now the code contains an unnecessary workaround

Or this situation:

1. I run into a problem when using Porcupine.
2. I don't fix it immediately. Instead, I create an issue, and I add documentation that shows how to work around the issue along with a link to it.
3. A long time passes.
4. I fix the issue.
5. Now the documentation contains an outdated and confusing workaround.

To fix the outdated code or docs, it might be nice to get a notification somewhere whenever an issue is closed but there is a link to that issue. That said, getting new issues just after fixing an issue could get annoying and confusing.

Maybe a better fix would be a script that finds all issue comments that were added before the corresponding issue was closed? This could be checked with GitHub's JSON API and git blame.