Modify issue template to keep unwanted issues out

There seems to be a lot password cracking requests lately which acts like a positive feedback loop - those are indexed and new people are directed to john repository (which also means we should be removing rather than closing). I've seen other github repositories use issue templates to provide steps how to file a bug, we could do the same to inform people that password cracking requests will be rejected.

I believe this is the procedure to do that: https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository