Updating documentation for Preset names and Preset 0.

[MichaelCrimando]

A current problem we're having is that there's no consistent documentation with preset 0. Should it be first in the preset list or last? This matters if you're setting custom preset names, since the app just sends an array of strings to name the presets. So if preset 0 is in the wrong spot, it throws off all the preset names. Currently Pandora considers it as preset 10 vs iHeartRadio considers it as preset 0.

This came up because we've never had a sync that can use 10 presets AND show the preset label.
sync3 only does presets 1-8 and shows labels.
sync1 does 10 presets but no labels

[MichaelCrimando]

@theresalech can you give this a review plz?

[joeygrover]

@MichaelCrimando the README.md is generated from the actual xml file MOBILE_API.xml . Sorry this can be a bit confusing. The XML file is the source of truth, we generate the README from it, then copy that into the developer portal.