Re: [PATCH] alias: restore support for simple dotted aliases

That is a challenge we are going to have to consider. I think reserving `command` is a worthwhile compromise, but obviously we cannot do that for arbitrary future keys such as `help`, `hidden`, etc.

One possible compromise would be to reserve `command` and `alias-*`, as neither seems very likely to exist in users' historical alias names.

A new namespace makes the most sense from a namespace-pollution point of view, but I struggle to see that as good UX. Even a separate namespace only for alias metadata would make more sense to me than moving aliases entirely, since subsection aliases with just `command` will likely be far more common than any future metadata keys, but this is not something I see as a good solution either.