How do I make a link to an Urbit group?

Urbit users can click on special hyperlinks of protocol urbit+webgraph that allow them to zip straight onto a group or a particular post of a conversation.  The general format of these URLs is:

web+urbitgraph://group/~shippes-sigile/group-name/

For a deep link into a post (normally achievable from the Groups app by tapping on a post's controls and selecting copy link), it can look like this:

web+urbitgraph://group/~bollug-worlus/urbit-index/graph/~bollug-worlus/index-weekly/170141184505590270664488304136155037696