Update GitCheatSheet to align with workflow

This commit restructures GitCheatSheet.txt to align with the workflow we're all supposed to
be following.. In particular, the commands you're likely to want to run are different when
working with a feature branch, so this way of organizing it reflects that.

This is mostly just reordering the instructions in the file to align with the workflow at the top.
That's true, but if you pipe it to less it actually wraps the long lines (probably because git is using some options for less). This is the simplest way to achieve line wrapping that I've found. Try it, it works for me. Of course, I would prefer it if everybody manually wrapped line lines in their commit messages, but some of us are not doing that.