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

Also:

* Be a bit more precise on the use of the term 'version'.
* Drop use of the word 'stable' - that will only apply to CUE versions
  >= v1.
* Fix links to the issue tracker and the contribution guide.
* Make clear that pre-releases can be installed too via this mechanism,
  and that the releases page includes a list of release and
  pre-releases.

Signed-off-by: Paul Jolly <[email protected]>

README.md

@@ -1,16 +1,17 @@
 # `setup-cue`
 
-***Install a specific [CUE](https://cuelang.org) CLI version on your Github
+***Install a specific [CUE](https://cuelang.org) CLI version on your GitHub
 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
+Use this action in your GitHub Actions workflow to install a specific version of
+[CUE](https://cuelang.org) on your runner. The input `version` is a
+[version](https://go.dev/ref/mod#versions) string like `v0.6.0`, or
+`v0.6.0-beta.1`. You can also use the keyword `latest` (default) to use the
+latest release of `cue`. Releases and pre-releases of `cue` are listed
 [here](https://github.com/cue-lang/cue/releases).
 
 ```
-- uses: cue-lang/setup-cue@v1
+- uses: cue-lang/setup-cue@v1.0.0
   with:
     version: '<version>' # default is latest
   id: install
@@ -38,13 +39,13 @@ can be executed directly in later workflow steps. It is also stored in the
 
 ## Issues/Discussions
 
-Please use the [main CUE repository](https://github.com/cue-lang/cue) to raise
-issues or start discussions about the `setup-cue` action.
+Please use the [main CUE repository](https://github.com/cue-lang/cue/issues) to
+raise issues or start discussions about the `setup-cue` action.
 
 ## Contributing
 
 This project follows the [CUE Contribution
-Guide](https://github.com/cue-lang/cue/blob/master/doc/contribute.md).
+Guide](https://github.com/cue-lang/cue/blob/master/CONTRIBUTING.md).
 
 ## Thanks