Add Truck Speed Limit field

[arch0345]

This PR adds a field for maxspeed:hgv, which I've added to the Motorway, Trunk Road, and Primary Road presets.

[tyrasd]

would you like to add this field also to the US+Canada regional version of the primary_link preset? primary_link-US-CA.json

[arch0345]

would you like to add this field also to the US+Canada regional version of the primary_link preset? primary_link-US-CA.json

Most primary links in the US/Canada only have an advisory speed limit. Currently there are only 2 primary links in the US/Canada with maxspeed:hgv: https://overpass-turbo.eu/s/1k3g

[tyrasd]

You mean the corresponding appropriate tag for the US/CA would be maxspeed:hgv:advisory? Ok, I guess we can skip it then

[arch0345]

Whoops, just realized I added it to the Primary Link preset instead of the Primary Road preset.