Where is out-of-source module's `module.conf` syntax documented? (e.g. `mod_freetdm|https://github...`)

I found these modules.conf snippets that I haven’t seen before, and I’m wondering where it is documented and if there are other rules that I don’t know of?

and

mod_kazoo|https://github.com/freeswitch/mod_kazoo.git -b master

I started digging into the source to figure it out, but I’m taking a break after not having been able to find much in the span of an hour. As far as I can tell, bootstrap.sh hasn’t got much to do with parsing modules.conf. The parts that I found relevant(?) in conifigure.ac and Makefile.am are the ones below, but these would never touch the source URL:

I also tried looking up keywords git and clone in the FreeSWITCH repo, found a ton of utility shell scripts, so maybe one of them will be the key.