docs: point at the latest release, and only ask for natives that exist

[jcant0n]

The README named a specific tag, so it went stale the moment upstream published
anything and had to be edited on every bump. GitHub's /releases/latest never
does. But a link to "latest" under the words "generated from this release" would
have been a lie between bumps, so the sentence now says what is true: the binding
tracks the latest stable release, and the revision actually vendored lives in
binding.yml, which the CD maintains.

Also stops asking for native artifacts when the job that builds them was skipped.
It is skipped whenever the release has not moved -- most runs, and every republish
of work already merged -- and downloading artifacts that were never produced fails
the step and takes the publish with it.

[github-actions]

API gate: additive

Every symbol that existed still exists, unchanged. Nothing that compiled before stops compiling.

Target framework	Added	Removed
net10.0	+0	-0

_{Enum and constant values are part of the measured surface: a renumbering keeps compiling and sends the wrong number to the driver, so it counts as a removal.}