How to regenerate `docs/`?

There are "Update docs" commits (https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/commits/master/docs) but there doesn't seem to be a script to do this in one fell swoop for all crates, had to come up with my own contraption and added a mv (+ documented it) when doing 75ba9eaf.

Not to mention these inconsistencies:

• Only few crates have doc_target_path: the rest ends up in vendor.md;
  • If this is set however, the output path becomes relative to the config directory (so where Gir.toml is found) instead of docs/<crate name>/docs.md;
• Gir requires an output directory to be set with -o but ignores it, stuff ends up in the wrong place.

Have I missed something or were the previous commits fixed up by hand?