feat(docs): example usage in README

README.md

@@ -10,3 +10,47 @@ just like Kubernetes with its resources and operators.
 
 > [!WARNING]
 > This project is currently under heavy development and not stable.
+
+## Example usage
+
+```yaml
+# example/my-manifest.yaml
+
+apiVersion: example.com/v1alpha1
+kind: MyManifest
+
+metadata:
+  name: my-manifest-1
+
+spec:
+  message: hello, world
+```
+
+```go
+import "github.com/yannickkirschen/manifesto"
+
+type MySpec struct {
+    Message string `yaml:"message" json:"message"`
+}
+
+func MyListener(pool *manifesto.Pool, action manifesto.Action, manifest manifesto.Manifest) {
+    // Do something with manifesto
+}
+
+func main() {
+    manifest := manifesto.ParseFile("example/my-manifest-1.yaml", &MySpec{}, &MySpec{})
+    spec :=  manifest.Spec.(*MySpec) // Do something with spec
+
+    pool := manifesto.CreatePool()
+    pool.Listen(MyListener)
+
+    pool.Apply(manifest)                     // Calls all listeners
+    pool.ApplyPartial(MyListener, *manifest) // Calls all listeners, except the specified one
+    pool.ApplySilent(*manifest)              // Does not call any listener at all
+
+    key := manifesto.CreateKey()          // Based on apiVersion and kind
+    theManifest, ok := pool.GetByKey(key) // Get the manifest and check existence
+
+    pool.Delete(key) // Gets ignored if the key does not exist
+}
+```