Translate Getting Started Guide to Typed, #25998

* convert example code
* update doc content
* update diagrams
* rewrite parental supervison part

akka-docs/src/test/java/jdocs/sharding/ClusterShardingTest.java

@@ -156,7 +156,7 @@ public class ClusterShardingTest {
   static//#counter-actor
   public class Counter extends AbstractPersistentActor {
 
-    public static enum CounterOp {
+    public enum CounterOp {
       INCREMENT, DECREMENT
     }