doc: update README.md to reflect v0.6.0 release

Also be a bit more precise on the use of the term version.

Signed-off-by: Paul Jolly <paul@myitcv.io>

README.md

@@ -4,10 +4,10 @@
 Actions runner***
 
 Use this action in your github actions workflow to install a specific version of
-[CUE](https://cuelang.org) on your runner. `version` is a semantic version
-string like `v0.4.0`. You can also use the keyword `latest` (default) to use the
-latest stable release of `cue`. Releases of `cue` are listed
-[here](https://github.com/cue-lang/cue/releases).
+[CUE](https://cuelang.org) on your runner. The input `version` is a
+[version](https://go.dev/ref/mod#versions) string like `v0.6.0`. You can also
+use the keyword `latest` (default) to use the latest stable release of `cue`.
+Releases of `cue` are listed [here](https://github.com/cue-lang/cue/releases).
 
 ```
 - uses: cue-lang/setup-cue@v1