adding usage

README.md

@@ -1,7 +1,7 @@
 # Yarn & Percy CI
 Build with Yarn, Snapshot with Percy
 
-GitHub Action to build your project with Yarn followed by Percy snapshots. 
+GitHub Action to build your project with Yarn followed by Percy snapshots.
 
 ## Under development
 
@@ -10,3 +10,20 @@ GitHub Action to build your project with Yarn followed by Percy snapshots.
 You'll need to set up a secret `PERCY_TOKEN`.
 
 Read more about [secrets with GitHub](https://help.github.com/en/articles/virtual-environments-for-github-actions#creating-and-using-secrets-encrypted-variables) and [Percy Token](https://docs.percy.io/docs/environment-variables).
+
+## How to upcase
+
+```yaml
+on: [push]
+
+jobs:
+  yarn_percy_ci_job:
+    runs-on: ubuntu-latest
+    name: Build with Yarn, Snapshot with Percy
+    steps:
+    - name: Yarn & Percy CI
+      id: yarn-percy-ci
+      uses: jpvalery/yarn-percy-ci@master
+      env:
+        PERCY_TOKEN: ${{ secrets.PERCY_TOKEN }}
+```