use more imperative-like command names.
Aliases are used to keep old commands working.
Also add an explicit deprecation message in swh-scheduler's help message.
$ swh scheduler Usage: swh scheduler [OPTIONS] COMMAND [ARGS]... Software Heritage Scheduler tools. Use a local scheduler instance by default (plugged to the main scheduler db). Options: -C, --config-file FILE Configuration file. -d, --database TEXT Scheduling database DSN (imply cls is 'local') -u, --url TEXT Scheduler's url access (imply cls is 'remote') --no-stdout Do NOT output logs on the console -h, --help Show this message and exit. Commands: rpc-serve Starts a swh-scheduler API HTTP server. start-ghtorrent Starts a ghtorrent consumer service. start-listener Starts a swh-scheduler listener service. start-runner Starts a swh-scheduler runner service. start-updater Starts a scheduler-updater service. task Manipulate tasks. task-type Manipulate task types.