CLI gen: only define about, not long_about

[david-crespo]

Explanation in code comment. I was dismayed to learn that in our CLI, -h and --help display different information. clap does this when you define both about and long_about. This PR stops doing that.

A less invasive alternative would be to keep defining about and long_about, but include both summary and description in long_about instead of just description. That would still be an improvement on the status quo, so I'd be in favor of it, but it does not fix the fact that -h and --help do different things, which to me is a little bizarre.

Before

-h displays the short description, --help displays the long one, but they are disjoint.

After

The downside is we lose the cute listing of one-liners because the full descriptions get jammed in there. Personally I prefer this overall and I'm not sure more info in the list is necessarily a bad thing, but I can see how someone might disagree.

[david-crespo]

Hand-written commands in the CLI will still have the about/long_about split, but in the better way that I describe above as the less-invasive alternative.

🤖 how hand-written commands in oxide.rs work

Every hand-written subcommand (cmd_api, cmd_auth, cmd_disk, cmd_instance, cmd_net, cmd_support_bundle, cmd_completion) is a #[derive(Parser)] with #[command(verbatim_doc_comment)] and a multi-paragraph /// doc comment. clap's derive macro maps that the same way progenitor used to:

• first paragraph (up to the first blank line) → about
• whole comment → long_about

So e.g. oxide api -h shows only:

Make an authenticated HTTP request to the Oxide API and print the response.

while oxide api --help shows the full multi-paragraph prose about --field, @file, --paginate, etc.