Mention the new working-directory input in the README

Author: eregon

README.md

@@ -134,6 +134,11 @@ This uses the [cache action](https://github.com/actions/cache).
 The code above is a more complete version of the [Ruby - Bundler example](https://github.com/actions/cache/blob/master/examples.md#ruby---bundler).
 Make sure to include `use-ruby` in the `key` to avoid conflicting with previous caches.
 
+### Working Directory
+
+The `working-directory` input can be set to resolve `.ruby-version`, `.tool-versions` and `Gemfile.lock`
+if they are not at the root of the repository, see [action.yml](action.yml) for details.
+
 ## Windows
 
 Note that running CI on Windows can be quite challenging if you are not very familiar with Windows.

action.yml

@@ -6,15 +6,15 @@ branding:
   icon: download
 inputs:
   ruby-version:
-    description: 'Engine and version to use, see the syntax in the README. Reads from .ruby-version if unset.'
+    description: 'Engine and version to use, see the syntax in the README. Reads from .ruby-version or .tool-versions if unset.'
     required: false
     default: 'default'
   bundler:
     description: 'The version of Bundler to install. Either none, 1, 2, latest or Gemfile.lock. The default tries Gemfile.lock and otherwise uses latest.'
     required: false
     default: 'default'
   working-directory:
-    description: 'The working directory to use for this path. Useful if files like .ruby-version are somewhere other than the root of your repository. Defaults to leaving it unchanged.'
+    description: 'The working directory to use for resolving paths for .ruby-version, .tool-versions and Gemfile.lock.'
     required: false
     default: '.'
 outputs: