move code to src/test

* so that it compiles and tests pass
* fix some additional snip references in getting started

akka-docs/src/test/java/jdocs/stream/Main.java

@@ -0,0 +1,9 @@
+package jdocs.stream;
+
+//#main-app
+public class Main {
+  public static void main(String[] argv) {
+    // Code here
+  }
+}
+//#main-app