Contribution guideline

Is it already the time to have a central conribution guideline, one like GitHub proposes us to have here github.com/vassalengine/vassal/community?

And also, should we make a list of easy-to-do changes, things that newcomers that feel somewhat intimidated by the big discussions and complex changes could take and propose their first easy PRs? We could use the checkstyle warnings for this, spelling errors, or missing unit tests.