add SingletonBehaviour usage example

Assets/Scripts/Util/SingletonBehaviour.cs

@@ -21,3 +21,30 @@ public abstract class SingletonBehaviour<T> : MonoBehaviour where T : SingletonB
 		}
 	}
 }
+
+/* Usage example
+
+// SomeManager.cs:
+// A singleton script that manages something
+public class SomeManager : SingletonBehaviour<SomeManager> {
+
+	public void DoSomething(MonoBehaviour someScript) {
+		// some code here, just like any other behaviour might have
+	}
+
+}
+
+// SomeNormalScript.cs:
+// A normal script that needs to access the single instance of SomeManager that should be present
+// in the scene
+public class SomeNormalScript : MonoBehaviour {
+
+	void Awake() {
+		SomeManager.instance.DoSomething(this);
+	}
+
+	// more behaviour code
+
+}
+
+*/