[Tagging] cycleway:lane=advisory

[Tobias Zwick]

> But the bogus option would be perfect for Italy.
> Until >Septeber 2020 we did not have advisory lanes. 

Interesting. If the de-facto situation in Italy is that all cycleway 
lanes are exclusive, I would suggest discussing in the Italian community 
if it made sense to do an automated edit in Italy to add 
cycleway(:left/right/both):lane=exclusive to all cycle lanes edited 
before Sept 2020.

> A question to Tobias: how do you handle this in Germany?  You must have 
> a major rettaging process under way.

Nothing organised, as far as I know. The point is, that with "Option 1" 
(just defining a subtag), no retagging effort is necessary. Just as 
there is no retagging process to add artwork_type=* to tourism=artwork, 
nor is it necessary.

That having said, it is possible to add this information with 
StreetComplete. Every 4 years, users of StreetComplete are asked if 
"this [is] still the cycleway situation here?", with visualization of 
what is currently tagged. Read more about it here:
https://wiki.openstreetmap.org/wiki/Microgrants/Microgrants_2020/Proposal/Map_Maintenance_with_StreetComplete/Report

I am planning to add a feature to the app where one can see all cycle 
tracks and lanes color-coded on an overview map so one can add the lane 
type in a more organised and efficient fashion. Read more about it here:
https://github.com/streetcomplete/StreetComplete/issues/2461

Tobias