docs: add tiny reference for the .tool-versions

See actions#402

README.md

@@ -181,9 +181,9 @@ If both the `go-version` and the `go-version-file` inputs are provided then the
 
 If the file contains only major and minor (e.g. 1.18) tags, the action will search for the latest available patch version sequentially in the runner's directory with the cached tools, in the [version-manifest.json](https://github.com/actions/go-versions/blob/main/versions-manifest.json) file or at the go servers.
 
-### If the go.mod file
+### If the go.mod or .tool-versions files
 
-The `go-version-file` input accepts a path to a `go.mod` file or a `go.work` file that contains the version of Go to be used by a project. As the `go.mod` file contains only major and minor (e.g. 1.18) tags, the action will follow the above-mentioned approach.
+The `go-version-file` input accepts a path to a `go.mod` file, `.tool-versions` file or a `go.work` file that contains the version of Go to be used by a project. As the `go.mod` file contains only major and minor (e.g. 1.18) tags, the action will follow the above-mentioned approach.
 
 > The action will search for the `go.mod` file relative to the repository root