Update docs on removal of mapbox:// protocol

[wipfli]

Launch Checklist

This pull request updates jsdocs comments on the removal of the mapbox:// protocol, which happened in the TypeScript migration #209.

The style specification is updated too, to reflect the removal of mapbox:// and its major version is bumped from 14 to 15.

Since I was cleaning up the docs, I also replaced Mapbox with MapLibre and removed links to mapbox.com.

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!
• Briefly describe the changes in this PR.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality.
• Document any changes to public APIs.
• Post benchmark scores.
• Manually test the debug page.
• Suggest a changelog category: bug/feature/docs/etc. or "skip changelog".
• Add an entry inside this element for inclusion in the maplibre-gl-js changelog: <changelog></changelog>.

[github-actions]

Bundle size report:

Size Change: 0 B
Total Size Before: 194 kB
Total Size After: 194 kB

Output file	Before	After	Change
maplibre-gl.js	185 kB	185 kB	0 B
maplibre-gl.css	9.49 kB	9.49 kB	0 B

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No major changes

[HarelM]

Nice work!!

[HarelM]

Also related to #27