`dnst keygen` list of algorithms and option to specify key size hard to find.

[ximon18]

$ dnst keygen -h
Generate a new key pair for a given domain name

Usage: dnst keygen [OPTIONS] --algorithm <algorithm> <domain>

Arguments:
  <domain>  The domain name to generate a key for

Options:
  -a, --algorithm <algorithm>  The signature algorithm to generate for
  -k                           Generate a key signing key instead of a zone signing key
  -s, --symlink[=<how>]        Whether to create symlinks [default: no] [possible values: no, yes, force]
  -h, --help                   Print help (see more with '--help')

Based on this one might ask which algorithms are supported (as -a list only works in LDNS emulation mode, not in DNST mode) or how do I specify an RSA key length.

It is possible to learn how to do both, but only from the long help:

$ dnst keygen --help
...
Options:
  -a, --algorithm <algorithm>
          The signature algorithm to generate for
          
          Possible values:
          - RSASHA256[:<bits>]: An RSA SHA-256 key (algorithm 8) of the given size (default 2048)
          - ECDSAP256SHA256:    An ECDSA P-256 SHA-256 key (algorithm 13)
          - ECDSAP384SHA384:    An ECDSA P-384 SHA-384 key (algorithm 14)
          - ED25519:            An Ed25519 key (algorithm 15)
          - ED448:              An Ed448 key (algorithm 16)
...

Maybe the -h output could direct users to --help to learn about the available algorithms and how to specify key size?