Now that we plan to import share-alike data, we need to tell users where
they can find out which OpenAddresses data is actually share alike. The
state.txt file on the OpenAddresses website has that information.
Simplifies documentation language based on [retext-mapbox-standard](https://github.com/mapbox/retext-mapbox-standard).
There are still several things that don't pass linter muster, but they're key terms for the product (namely "prioritize").
Revise all data source descriptions to follow a common pattern:
1.) What, in brief, is it?
2.) Why is it useful to include in Mapzen Search?
3.) What is the license?
I'd love some further help with tweaks in a couple areas that I think
are still lacking:
* keeping it informative without sounding too sales-pitchy. I really
want to list the good reasons why we use each data source without making
it sound like we are trying to sell someone something they don't need.
* Following the common format without sounding too templated
* Not hating on Geonames. It's a good dataset and we include it for a
reason, but it is a bit different and we also want to capture that
honestly.