Open PRs to the upstream repo

[ssiccha]

First we need to clean up our version of the gap-lesson and maybe also our git history. Then changes should be divided sensibly into PRs.

[olexandr-konovalov]

This is most welcome and appreciated. Looking forward to this.

[olexandr-konovalov]

Hi @ssiccha @DominikBernhardt @cschoennenbeck - I have updated https://github.com/carpentries-incubator/gap-lesson to the new format, called Workbench - please see the comment at carpentries-incubator#35 (comment) with further details, questions and suggestions.