Refactor the index page to match the sidebar

[ericholscher]

This is basically just pulling the main bits from the sidebar,
and putting them in the front page.

[agjohnson]

This also looks great, it's much better.

Re emojis: I like including some, but I prefer how this doesn't use emojis as bullet points. It looks better without them to me.

I think graphic elements -- images of our UIs or even just supporting images -- do a better job of bringing life to the docs.

[ericholscher]

Yea, I mostly just got annoyed at having to figure out emojis and killed them to make it easier to move forward. I think we could play around with them sparingly.

There's definitely additional work here to do, but this is a reasonable first step.

[humitos]

I like the idea of using emojis/icons. Here is an example where I think they work great: https://about.readthedocs.com/comparisons/github-pages/ --where it uses an emoji/icon kind of related to the feature.