Several passages described Flox the way an outsider describes another
company's product: "the flox packages ship their own Nix", "flox brings
its own Nix". We maintain Flox, so the possessive framing is wrong. The
distinction is between "ships their own Nix", which is what an observer
writes, and "ships with Nix", which is what the maintainer writes.

Most of these are prose, but one is not. The string in `core.warning`
that fires when reinstalling from a reference with no version ordering
is printed into the user's job log, and the `version` input description
in `action.yml` appears in the Marketplace listing. The README passages
render on the repository page. The remaining three are comments that no
user sees, corrected for consistency.

That warning also opened with a sentence fragment, and "afterwards" is
now "afterward".

Nothing behavioral changes. `dist/index.js` is regenerated because these
strings live in the bundle.