doc: added some cli doc strings for asp commands

Motivation

I was just getting started up using the project and saw no docs strings for the aspd commands so I added some

For command aspd

before

Commands:
  create
  set-config
  start
  drain
  get-mnemonic
  drop-oor-conflicts
  rpc
  help                Print this message or the help of the given subcommand(s)

Options:
      --datadir <DATADIR>  the data directory for aspd, mandatory field for most commands
  -h, --help               Print help
  -V, --version            Print version

after

Commands:
  create              Create and configure asp server
  set-config          Set and update asp config
  start               Start asp server
  drain               Drain funds of asp
  get-mnemonic        Retrieve 12 word seed phrase
  drop-oor-conflicts
  rpc                 Run RPC commands
  help                Print this message or the help of the given subcommand(s)

Options:
      --datadir <DATADIR>  the data directory for aspd, mandatory field for most commands
  -h, --help               Print help
  -V, --version            Print version

For command aspd rpc

before

Commands:
  balance
  get-address
  trigger-round
  stop           Stop aspd
  help           Print this message or the help of the given subcommand(s)

Options:
      --addr <ADDR>        [default: 127.0.0.1:3536]
      --datadir <DATADIR>  the data directory for aspd, mandatory field for most commands
  -h, --help               Print help

after

Commands:
  balance        Get asp balance
  get-address    Get asp address
  trigger-round  Start a new asp round
  stop           Stop aspd
  help           Print this message or the help of the given subcommand(s)

Options:
      --addr <ADDR>        [default: 127.0.0.1:3536]
      --datadir <DATADIR>  the data directory for aspd, mandatory field for most commands
  -h, --help               Print help