update README urlTemplate

[jermahs]

Was following the instructions, but 'https://api.tiles.mapbox/v4...' didn't work. I had to remove the 'tiles' portion... so it was: "https://api.mapbox.com/v4/{id}/{z}/{x}/{y}@2x.png?access_token={accessToken}"

[johnpryan]

Weird! It doesn't seem to matter for me. I am using:

https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}@2x.png?access_token={accessToken}

but the .tiles can be removed, and matches the documentation

https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}@2x.png?access_token={accessToken}

I also see api.tiles in various places in their documentation so I'm not sure what the difference is to be honest.

[jermahs]

Hm I just created the account and it kept giving me a 401 with the tiles included.

[johnpryan]

Ok, not sure what's going on with my setup, but I think 090d533 is the correct change. Thanks for filing an issue!