+doc add depenedency note to docs #20732 (#20761)

akka-docs/rst/java/http/routing-dsl/testkit.rst

@@ -9,7 +9,7 @@ response properties in a compact way.
 
 To use the testkit you need to take these steps:
 
-* add a dependency to the ``akka-http-testkit-experimental`` module
+* add a dependency to the ``akka-http-testkit`` module
 * derive the test class from ``JUnitRouteTest``
 * wrap the route under test with ``RouteTest.testRoute`` to create a ``TestRoute``
 * run requests against the route using ``TestRoute.run(request)`` which will return

akka-docs/rst/scala/http/routing-dsl/testkit.rst

@@ -4,6 +4,9 @@ Route TestKit
 One of Akka HTTP's design goals is good testability of the created services.
 For services built with the Routing DSL Akka HTTP provides a dedicated testkit that makes efficient testing of
 route logic easy and convenient. This "route test DSL" is made available with the *akka-http-testkit* module.
+To use it include the following dependency::
+
+  "com.typesafe.akka" %% "akka-http-testkit" % "@version@"
 
 
 Usage