Discuss: Add Telemetry to mdoc

[joelmartinez]

I'd like to consider adding telemetry to mdoc, to gather information about usage. This can be as simple as just an event when a subcommand is run (to get usage stats), to gathering more detail about how many types and members are added, updated, and removed during an mdoc update run (for example).

If we did this, I think we should follow the example of the dotnet cli ... and be very transparent about what we gather, and make it easy to opt-out.

Thoughts would be welcome.

[joelmartinez]

/cc @conceptdev, @lobrien, @dend, @jonpryor

Would love to hear ideas about what about be useful to capture (obviously keeping in mind GDPR, etc).