Update README.md

Author: stefanoeb

README.md

@@ -1,4 +1,21 @@
-# GitHub Jest runner
+# ⚠️⚠️⚠️ You don't need this action ⚠️⚠️⚠️
+
+Github Actions have everything that you need to run your jest tests, to do that simply use the `run` commands like so:
+```yml
+name: CI
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install modules
+      run: yarn
+    - name: Run tests
+      run: yarn test
+```
+
+---
 
 This action executes Jest test runner without any previous action/build step or Docker required.