<pack> is always name@version. See Rule packs for
the concepts.
nanny rules add
Vendors a pack into.nanny/rules/ and declares it in [rules] extends.
nanny.toml are
preserved.
Fails without writing anything if the pack is unpinned, if --from holds a
different pack than you named, or if the contents do not match the digest in the
manifest.
nanny rules list
Every pack installed in this project, with its version, whether its contents were verified on install, and how many rules it registers.nanny rules remove
Deletes the vendored pack and removes its line from[rules] extends.