Add fix message for route highway mismatch

[Famlam]

This is related to #2043.
It adds a fix suggestion to the Way access mismatch relation route=* errors

The question whether highway=pedestrian for bicycles should be exempted (e.g. the actual issue that was reported) isn't resolved yet. See (from that issue)

we could just exclude pedestrian. Out of the 32 countries listed on that wiki, 12 permit cyclists on highway=pedestrian. (Just like cycleway is excluded for foot relations because it differs so much per country)

[frodrigo]

Thank you.