Update README

README.md

@@ -1,2 +1,31 @@
-Test
+# cp-all-in-one-action
 
+This action runs [cp-all-in-one](https://github.com/confluentinc/cp-all-in-one/tree/latest/cp-all-in-one), a Docker Compose for Confluent Platform.  See [Confluent documentation](https://docs.confluent.io/platform/current/tutorials/build-your-own-demos.html) for details.
+
+# Usage
+
+- `service`: up to which service in the docker-compose.yml file to run.  Default is none, so all services are run
+- `github-branch-version`: which GitHub branch of [cp-all-in-one](https://github.com/confluentinc/cp-all-in-one) to run.  Default is `latest`.
+
+Example to run ZooKeeper and broker on Confluent Platform `7.1.0`:
+
+```yaml
+
+    steps:
+
+      - name: Run Confluent Platform (Confluent Server)
+        uses: ./.github/actions/cp-all-in-one
+        with:
+          service: broker
+          github-branch-version: 7.1.0-post
+```
+
+Example to run all services on `latest`:
+
+```yaml
+
+    steps:
+
+      - name: Run Confluent Platform (Confluent Server)
+        uses: ./.github/actions/cp-all-in-one
+```