Remove manage register command from docs

[dklimpel]

manage register is not a valid command anymore.

mas-cli manage
Manage the instance

Usage: mas-cli manage [OPTIONS] <COMMAND>

Commands:
  verify-email               Mark email address as verified
  set-password               Set a user password
  issue-compatibility-token  Issue a compatibility token
  provision-all-users        Trigger a provisioning job for all users
  kill-sessions              Kill all sessions for a user
  lock-user                  Lock a user
  unlock-user                Unlock a user
  help                       Print this message or the help of the given subcommand(s)

Options:
  -c, --config <CONFIG>  Path to the configuration file
  -h, --help             Print help

[sandhose]

Looks like this was removed a while ago. Thanks!