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.
Add hooks mechanism and th-opening-default-tiddlers-list hook

see: https://github.com/Jermolene/TiddlyWiki5/issues/1064
add /dev docs
Remove alert from addHook.

Thanks to @tobibeer
hide static links for any system tiddlers prefixed "$:/"

also added underlined format to make it at least stand out a little,
even if not a link
Update cla-individual.md
also hide shadows, no underlined url
Browser compatibility docs
#371 focus title field on edit

* enhanced edit-text widget with a "focus=true" attribute
* modified title template to make it focus and select by default
changed system tiddler filter check
Docs for new journal trick from Alberto Molina
Merge pull request #1141 from tobibeer/auto-focus-title-on-edit

#371 focus title field on edit
Coding style cleanup
Merge pull request #1133 from tobibeer/no-static-links-for-system-tiddlers

#1129 — hide static and github links for any system tiddlers prefixed "$:/" on tw.com
Merge pull request #1139 from Braincoke/patch-2

Update cla-individual.md
Merge pull request #1088 from Braincoke/patch-1

Update CodeMirror Documentation
Docs tweaks
House style tweaks for codemirror docs
Merge pull request #1118 from welford/hook

Add hooks mechanism and th-opening-default-tiddlers-list hook
Dev docs tweaks