Improve documentation on address for socket bind

sdk/lib/io/socket.dart

Index: sdk/lib/io/socket.dart
diff --git a/sdk/lib/io/socket.dart b/sdk/lib/io/socket.dart
index 48c864064f295f6c3bd1cb12ba3b6f322a3c8be8..6027a9ab65e730679eb5340d4ecfb5ec9da9e23a 100644
--- a/sdk/lib/io/socket.dart
+++ b/sdk/lib/io/socket.dart
@@ -16,6 +16,12 @@ abstract class RawServerSocket implements Stream<RawSocket> {
    * completes the server socket is bound to the given [address] and
    * [port] and has started listening on it.
    *
+   * The default value for [address] is 127.0.0.1, which will allow
+   * only incoming connections from the local host. To allow for
+   * incoming connection from the network use either the value 0.0.0.0
+   * to bind to all interfaces or the IP address of a specific
+   * interface.
+   *
    * If [port] has the value [:0:] (the default) an ephemeral port will
    * be chosen by the system. The actual port used can be retrieved
    * using the [:port:] getter.
@@ -51,6 +57,12 @@ abstract class ServerSocket implements Stream<Socket> {
    * completes the server socket is bound to the given [address] and
    * [port] and has started listening on it.
    *
+   * The default value for [address] is 127.0.0.1, which will allow
+   * only incoming connections from the local host. To allow for
+   * incoming connection from the network use either the value 0.0.0.0
+   * to bind to all interfaces or the IP address of a specific
+   * interface.
+   *
    * If [port] has the value [:0:] (the default) an ephemeral port will
    * be chosen by the system. The actual port used can be retrieved
    * using the [port] getter.