Create cider-doc-map and add "\C" versions of the keys when it makes sense.

Very nice initiative to create a doc map. Thanks. 

This patch adds a couple of control prefixed keys. For my brain <kbd>C-c C-d C-d</kbd> is much more convenient than <kbd>C-c C-d d</kbd>.
I think I've said this a few times - let's leave this keymap (and it's menu) as it was and modify it the future. Binding half the commands here doesn't make a lot of sense. Doing too much changes at once is rarely a good idea.