add usage examples

closes #1

examples/containerized-krm/README.md

@@ -0,0 +1,16 @@
+# Container Plugin Example
+
+This example runs `YqTransformer` as a **containerized KRM function**.
+
+## Locate the plugin image
+
+The `config.kubernetes.io/function` annotation in `yq-transformer.yaml`
+points to the plugin's image address in the `container.image` key.
+
+## Build with alpha plugins enabled
+
+```bash
+kustomize build --enable-alpha-plugins .
+```
+
+You should see a label `environment: dev` added to one of the Deployments.