Initial docs updates

[jhamrick]

This is just an initial PR to start updating the documentation. This:

1. Renames "ipython" to "jupyter"
2. Moves the example notebooks into the docs folder and converts them to rst (though this is not currently automated in anyway -- I just ran jupyter nbconvert --to rst)
3. Splits apart index.rst into a few separate files and then makes index.rst mostly just be a TOC

Things that are not addressed here:

1. Fleshing out the documentation or making it up-to-date
2. API docs

I figured I would make an initial PR to make sure I am heading in the right direction with this, and then address the second two things in separate PRs.

One question I had about this -- there is the ipython/nbconvert-examples repository. Do we want to move the examples in there to the nbconvert docs in this repository?

[takluyver]

Things like this will really want the output in the converted result as well as the code, I guess. Might need a custom template!

[jhamrick]

:-P Yes, definitely. Probably whatever build system we have for the notebook docs will need to run the notebooks first, so that the output gets included when converting to rst.

[takluyver]

I think this looks like a good start. We can steal the machinery to document config options from e.g. jupyter_console, where I've just set it up, but that can be in a later PR.

[jhamrick]

Ok, updated this to make the documentation be more up-to-date with the current version of nbconvert. I think it can still use more fleshing out and organizing a bit, but that can come later. I'll work next on getting the API docs working and building this on RTD.

[takluyver]

Awesome, merging.

[damianavila]

Nikola

[jhamrick]

Whoops, sorry Damien! I'll fix it in the next PR...

[damianavila]

No problem... I just see it and I did not want to forget about the typo...

[jhamrick]

Thanks!