Split up the doc pages

[asottile]

I've been wanting to do this for a while since the homepage is getting pretty long.

Basically what I want the homepage to be is a quickstart guide and have there be separate pages that go more in-depth

[struys]

Sounds good to me. A few nice to haves:

• A gif/video that shows how pre-commit works
• Since we're splitting up into pages, search with ctrl+f won't work anymore, maybe add this? - https://cse.google.com/cse/

[asottile]

I'd also like to incorporate #29 into this, or just inline examples

[awebdeveloper]

Also the hooks should be sorted by language too.

[asottile]

I'm not actually going to split up the pages, breaking existing links and ^F seems not a good idea.

[awebdeveloper]

if your referring to # links then you can still tag the quick links with id which will not break the old link