Documenting solution proposals for `highway=path`

Well, maybe. We do have mtb:scale as a tag that data consumers can use when deciding how to show MTB and cycle trails, but we know that out of lack of information, technical limitations** or laziness, many won’t.

** as a potential example of that, v1.0 of the Shortbread schema doesn’t include it. That’s not really a bug, since you can’t include everything.