'git mv' rst resources to md

This is mainly intended to keep the git history as neat as possible.
No actual conversion yet, so now both the rst and the paradox docs
are broken, which will be fixed in the next commits.

akka-docs/src/main/paradox/scala/code/docs/io/ScalaUdpMulticast.scala

@@ -0,0 +1,62 @@
+/**
+ * Copyright (C) 2009-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+
+package docs.io
+
+import java.net.{ InetAddress, InetSocketAddress, NetworkInterface, StandardProtocolFamily }
+import java.net.DatagramSocket
+import java.nio.channels.DatagramChannel
+
+import akka.actor.{ Actor, ActorLogging, ActorRef }
+import akka.io.Inet.{ DatagramChannelCreator, SocketOptionV2 }
+import akka.io.{ IO, Udp }
+import akka.util.ByteString
+
+//#inet6-protocol-family
+final case class Inet6ProtocolFamily() extends DatagramChannelCreator {
+  override def create() =
+    DatagramChannel.open(StandardProtocolFamily.INET6)
+}
+//#inet6-protocol-family
+
+//#multicast-group
+final case class MulticastGroup(address: String, interface: String) extends SocketOptionV2 {
+  override def afterBind(s: DatagramSocket) {
+    val group = InetAddress.getByName(address)
+    val networkInterface = NetworkInterface.getByName(interface)
+    s.getChannel.join(group, networkInterface)
+  }
+}
+//#multicast-group
+
+class Listener(iface: String, group: String, port: Int, sink: ActorRef) extends Actor with ActorLogging {
+  //#bind
+  import context.system
+  val opts = List(Inet6ProtocolFamily(), MulticastGroup(group, iface))
+  IO(Udp) ! Udp.Bind(self, new InetSocketAddress(port), opts)
+  //#bind
+
+  def receive = {
+    case b @ Udp.Bound(to) =>
+      log.info("Bound to {}", to)
+      sink ! (b)
+    case Udp.Received(data, remote) =>
+      val msg = data.decodeString("utf-8")
+      log.info("Received '{}' from {}", msg, remote)
+      sink ! msg
+  }
+}
+
+class Sender(iface: String, group: String, port: Int, msg: String) extends Actor with ActorLogging {
+  import context.system
+  IO(Udp) ! Udp.SimpleSender(List(Inet6ProtocolFamily()))
+
+  def receive = {
+    case Udp.SimpleSenderReady => {
+      val remote = new InetSocketAddress(s"$group%$iface", port)
+      log.info("Sending message to {}", remote)
+      sender() ! Udp.Send(ByteString(msg), remote)
+    }
+  }
+}