This changeset includes some fixes to documentation discovered while working on
node pools, but we didn't want to include in the node pool PRs so they can get
backported easily:
* namespace apply/delete commands are forwarded to the authoritative region
* deleting a namespace requires there are no non-terminal jobs in any of the
federated regions
* fixed a typo in the name of the `nomad.client.allocated.disk` metric
The new `namespace apply` feature that allows for passing a namespace
specification file detects the difference between an empty namespace
and a namespace specification by checking if the file exists. For most
cases, the file will have an extension like `.hcl` and so there's
little danger that a user will apply a file spec when they intended to
apply a file name.
But because directory names typically don't include an extension,
you're much more likely to collide when trying to `namespace apply` by
name only, and then you get a confusing error message of the form:
Failed to read file: read $namespace: is a directory
Detect the case where the namespace name collides with a directory in
the current working directory, and skip trying to load the directory.
