[Tagging] Mindistance=*

[Joachim]

I added mindistance=* to the section "statutory restrictions" on wiki
page for access=*
(https://wiki.openstreetmap.org/wiki/Key:access#Size_and_statutory_restrictions).
It's the signed minimum trailing distance, in metres as it is default
for lengths.

Current taginfo (on ways)
68 mindistance
47 mindistance:hgv
6 mindistance:hgv:lanes

It's often used for hgv vehicles in tunnels
(http://openstreetcam.org/details/27490/65) or on old bridges
(https://www.mapillary.com/map/im/6ZQory0nWk0uwwuenNM-Rw).

I will also create a wiki tag page. It there anything else to add?

regards Joachim