Improve commit message information of JS Guidelines

The Guidelines for the InterPlanetary JavaScript Projects contain information on how to format the commit message. It's based on a former Angular convention which is called "Conventional Commits". Read through http://conventionalcommits.org/ and see if it still matches our guidelines. If it does, link to it.

Also link to https://chris.beams.io/posts/git-commit/ which contains very good information on what a good commit message looks like. It also is in line with the Conventional Commits guidelines.