message: remove outdated instructions for 'doc' subcommand
diff: @@ -126,15 +126,6 @@ docker-compose run -d db
  docker exec -it <the container name goes here> psql -U cratesfyi
  ```
  -#### `doc` subcommand
  -
  -This subcommand will only build documentation of a crate.
  -It is designed to run inside a secure container.
  -
  -```
  -doc <CRATE_NAME>
  -```
  -
  #### Contact
  Docs.rs is run and maintained by [Rustdoc team](https://www.rust-lang.org/governance/teams/dev-tools#rustdoc).
  