feat(command): remove experimental CLI annotation

[doringeman]

Remove the experimental CLI annotation(s).

Before:

$ docker model
Usage:  docker model COMMAND

Docker Model Runner (EXPERIMENTAL)

EXPERIMENTAL:
  docker model is an experimental feature.
  Experimental features provide early access to product functionality. These
  features may change between releases without warning, or can be removed from a
  future release. Learn more about experimental features in our documentation:
  https://docs.docker.com/go/experimental/

Commands:
...

Now:

$ docker model
Usage:  docker model COMMAND

Docker Model Runner

Commands:
...