Rust comment explaining NoArgs struct has become `--help` message

[simonhollingshead]

comprehensive/comprehensive/src/assembly.rs

Line 1077 in 86e12bb

/// Convenience type that can be used as the `Args` associated type on

❯ ./helloworld-grpc-server --help
Convenience type that can be used as the `Args` associated type on any [`Resource`] that takes no command line arguments.

[`Resource`]: [`crate::v0::Resource`]

Usage: helloworld-grpc-server [OPTIONS]

Options:
      --grpc-port <GRPC_PORT>
          TCP port number for insecure gRPC server. If unset, plain gRPC is not served.
...

❯ ./helloworld-grpc-client --help
Convenience type that can be used as the `Args` associated type on any [`Resource`] that takes no command line arguments.

[`Resource`]: [`crate::v0::Resource`]

Usage: helloworld-grpc-client [OPTIONS] --client-uri <client-uri>

Options:
      --greet-interval <GREET_INTERVAL>
          [default: 5s]
...