UX: known "patterns" to be displayed also for "download"

[yarikoptic]

Currently --help only of ls has

$> dandi ls --help
Usage: dandi ls [OPTIONS] [PATHS]...

  List .nwb files and dandisets metadata.

  Patterns for known setups:
   - DANDI:<dandiset id>
   - https://dandiarchive.org/...
   - https://identifiers.org/DANDI:<dandiset id>
   - https://<server>[/api]/[#/]dandiset/<dandiset id>[/<version>][/files[?location=<path>]]
   - https://*dandiarchive-org.netflify.app/...
   - https://<server>[/api]/dandisets/<dandiset id>[/versions[/<version>]]
   - https://<server>[/api]/assets/<asset id>[/download]
   - https://<server>[/api]/dandisets/<dandiset id>/versions/<version>/assets/<asset id>[/download]
   - https://<server>[/api]/dandisets/<dandiset id>/versions/<version>/assets/?path=<path>
   - dandi://<instance name>/<dandiset id>[@<version>][/<path>]
   - https://<server>/...

and for download we need user to make a mistake first to display them.

• for ls it is actually a bit confusing: we say it operates on PATHs, but then talk about some "patterns" without providing context. Docstring (--help) and may be METAVAR (currently PATH now, but could be RI (Resource identifier)) should be adjusted to be more reflective of what we are talking about.
• I would call those "patterns" to be "Resource Identifier (URLs included) patterns"
• we need to add similar listing to download's --help

@satra -- may be you have also some ideas on how we should "name" and expose those all possibly "Resource Identifier patterns" we support?