Document that you can't add "attribution" property to a TileJSON-loaded vector source

[pathmapper]

mapbox-gl-js version: v0.46.0

browser: Chrome on Linux

Link to Demonstration

https://jsbin.com/kivaqajija/edit?html,output

Expected Behavior

According to the style spec it should be possible to add an attribution property:

https://www.mapbox.com/mapbox-gl-js/style-spec#sources-vector-attribution

Actual Behavior

Error: a source with a "url" property may not include a "attribution" property

[pathmapper]

The same for raster sources:
https://jsbin.com/caqenoxojo/edit?html,output

For raster-dem sources no error, but the attribution is not displayed:
https://jsbin.com/qiqoduheve/edit?html,output

[pathmapper]

Just found #5936 (comment), so the error for vector and raster sources is expected behaviour.

I guess for raster-dem sources it's just missing.

It would be useful if the docs would mention that it is not possible to use some properties if providing a TileJSON resource with the url property.

[asheemmamoowala]

Closed by #8232