+doc explain backpressure / reactive streams a bit

akka-docs-dev/rst/scala/code/docs/stream/FlowDocSpec.scala

@@ -56,11 +56,8 @@ class FlowDocSpec extends AkkaSpec {
     val source = Source(1 to 10)
     val sink = Sink.fold[Int, Int](0)(_ + _)
 
-    // materialize the flow
-    val materialized: MaterializedMap = source.to(sink).run()
-
-    // get the materialized value from the running streams MaterializedMap
-    val sum: Future[Int] = materialized.get(sink)
+    // materialize the flow, getting the Sinks materialized value
+    val sum: Future[Int] = source.runWith(sink)
     //#materialization-runWith
   }
 

akka-docs-dev/rst/scala/code/docs/stream/FlowGraphDocSpec.scala

@@ -33,15 +33,13 @@ class FlowGraphDocSpec extends AkkaSpec {
       val in = Source(1 to 10)
       val out = Sink.ignore
 
-      val broadcast = Broadcast[Int]
+      val bcast = Broadcast[Int]
       val merge = Merge[Int]
 
-      val f1 = Flow[Int].map(_ + 10)
-      val f3 = Flow[Int].map(_.toString)
-      val f2 = Flow[Int].map(_ + 20)
+      val f1, f2, f3, f4 = Flow[Int].map(_ + 10)
 
-      in ~> broadcast ~> f1 ~> merge
-            broadcast ~> f2 ~> merge ~> f3 ~> out
+      in ~> f1 ~> bcast ~> f2 ~> merge ~> f3 ~> out
+                  bcast ~> f4 ~> merge
     }
     //#simple-flow-graph
     //format: ON

akka-docs-dev/rst/scala/code/docs/stream/StreamPartialFlowGraphDocSpec.scala

@@ -51,7 +51,9 @@ class StreamPartialFlowGraphDocSpec extends AkkaSpec {
                   in3 ~> zip2.right
                          zip2.out ~> out
     }
+    //#simple-partial-flow-graph
     // format: ON
+    //#simple-partial-flow-graph
 
     val resultSink = Sink.head[Int]