[Tagging] usage of maxspeed:practical is described as recommended on wiki

[Mateusz Konieczny]

See https://wiki.openstreetmap.org/wiki/Talk:Key:surface#maxspeed:practical
for proposed change

_______________________________________________
Tagging mailing list
Tagging@openstreetmap.org
https://lists.openstreetmap.org/listinfo/tagging