Updated introduction

Author: shailen

dart_io_mini_samples/example/introduction.md

@@ -12,4 +12,11 @@ accomplish a task. For example, to read a file as a string you can use either
 the asynchronous `readAsString()` method from the File class, or its synchronous
 counterpart, `readAsStringSync()`.
 <strong>The examples below use only the asynchronous versions.</strong>
-</aside>
+</aside>
+
+See the
+[source on Github](https://github.com/dart-lang/dart-samples/tree/master/dart_io_mini_samples).
+
+After looking at the following code examples, refer to
+[Writing Command-line Apps: A Programmer's Guide](/docs/serverguide.html)
+for additional information about I/O, command-line apps, and servers.