Use of highway=cycleway for mtb trails

[c0nsumer (Steve Vigneau)]

@supsup

I think the discussion below Documenting solution proposals for highway=path - #116 by supsup

is also relevant. I think this thread is one more reason why we need
pathway=mtb_single_track

This is interesting, and I particularly agree with this: Documenting solution proposals for `highway=path` - #122 by Duja

I don’t think pathway= is the way to go. I believe the existing tags solve it. I don’t think there’s need to add something further.