Add an `upstream_url` or `info_url` field to the model

[twardoch]

Right now, "upstream" URLs that contain data about the axes are placed in the non-machine-readable part (the comment). It’d be useful to add an upstream_url or info_url field to the model, and put the URLs there, so the info becomes machine-readable.

[davelab6]

I'm tempted to close this and recommend such users just grep URLs out?

[felipesanches]

Having such data in a machine-readable data structure field instead of as comments facilitate tools that want to access the data via the python API. (no grepping).

No such need surfaced up to now, but it is a nice idea for someday (whenever some tools actually need that). Leave the issue open, @davelab6, as it seems to be a legitimate feature request.