Make API reference easier to find, add list of keyboard shortcuts somewhere

[henrebotha]

The docs do a great job of teaching things tutorial-style, but I'm desperately missing things like:

• A complete API reference page where I can just browse through a complete description of every single function.
• A complete keyboard shortcuts page where I can see every single keyboard shortcut.

If they exist, they're hard to find!

[yaxu]

There is a reference in the main UI, under the 'reference' tab. We might be lacking a keyboard shortcut though!

[yaxu]

Also it seems the reference is hard to find once the side/bottom bar is minimised?

[henrebotha]

Ah, I didn't think to check the REPL itself. I'm glad to have found it now, though it needs full text search; I notice it's quite hard to find something if you can't guess the right name for it.