Update action for new actions syntax

https://help.github.com/en/actions/automating-your-workflow-with-github-actions/metadata-syntax-for-github-actions

Dockerfile

@@ -1,10 +1,9 @@
-FROM ruby:2.6
+FROM ruby:2.7
 
-LABEL com.github.actions.name="StandardRB checks"
+LABEL com.github.actions.name="StandardRB"
 LABEL com.github.actions.description="Lint your Ruby code in parallel to your builds with StandardRB"
 LABEL com.github.actions.icon="code"
 LABEL com.github.actions.color="red"
-
 LABEL maintainer="Bryce Mecum <[email protected]>"
 
 COPY lib /action/lib

README.md

@@ -5,6 +5,40 @@ Based almost entirely off the [Rubucop Action](https://github.com/gimenete/ruboc
 
 ![](docs/images/screenshot.png)
 
+## Example usage
+
+Here's an example running a build matrix and StandardRB:
+
+```yml
+name: CI
+
+on: [push]
+
+jobs:
+  Build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: [ '2.5', '2.6', '2.7' ]
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Ruby ${{matrix.ruby}}
+      uses: actions/setup-ruby@v1
+      with:
+        ruby-version: ${{matrix.ruby}}
+    - name: Build and test with Rake
+      run: |
+        gem install bundler
+        bundle install --jobs 4 --retry 3
+        bundle exec rake
+  StandardRB:
+    runs-on: ubuntu-latest
+    steps:
+      - name: standardrb
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        uses: amoeba/standardrb-action@v2
+```
 
 ## Contributing
 

action.yml

@@ -0,0 +1,19 @@
+# https://help.github.com/en/articles/metadata-syntax-for-github-actions
+name: 'StandardRB'
+author: 'https://github.com/amoeba'
+description: 'Lint your Ruby code in parallel to your builds with StandardRB'
+outputs:
+  title:
+    description: 'The title of the check'
+  summary:
+    description: 'The description of the check'
+  annotations:
+    description: 'A reference to the code failing the check'
+env:
+  'GITHUB_TOKEN': 'Automatically set by Actions'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+branding:
+  icon: 'code'
+  color: 'red'