Make more customizable issues form #19

#18 introduces an issues template.
We could be even more specific/tailored to the application by using:
https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository#creating-issue-forms

However, this is currently in beta (only available for public repositories, and Im not sure we should invest alot of time in it atm).