Remove words such as simply and obviously from docs (#25095)

* One does not "simply"

* It's not obvious

* It's not really _that_ easily done

* Basically is basically a useless word

* Of course - if you already know how things work you wouldn't be reading the docs

* Clearly is maybe not so clear for everyone

* Just was just a bit harder as there are some uses that are just

akka-docs/src/test/java/jdocs/testkit/TestKitDocTest.java

@@ -271,7 +271,7 @@ public class TestKitDocTest extends AbstractJavaTest {
   public void demonstrateProbe() {
     //#test-probe
     new TestKit(system) {{
-      // simple actor which just forwards messages
+      // simple actor which only forwards messages
       class Forwarder extends AbstractActor {
         final ActorRef target;
         @SuppressWarnings("unused")