Update CodeMirror Documentation

I wish I could have added tiddlers to the documentation in order to put the mini-tutorials in tabs but I couldn't.
So it is a bit messy in my opinion, but I think it is a good start.

I have tested every configuration with Tiddlywiki v 5.1.4.
Merge pull request #1088 from Braincoke/patch-1

Update CodeMirror Documentation