Do not use pager for root `uv help` and improve after help hint (#4936)
Adds a nice hint at the bottom of `uv help` output indicating how to get
more details about a specific command, roughly matching Cargo's
interface.
We use the short help and skip the pager for the root `uv help` since
it's intended to be a landing page for the help interface more than an
in-depth display. This also matches Cargo, though I like that they have
the global options above the commands and I've not changed that here.