Fixed broken link on app_hardware to serial api reference docs.

chrome/common/extensions/docs/server2/templates/articles/app_hardware.html

 <h1>Accessing Hardware Devices</h1>
 
 
 <p>
 This doc shows you how packaged apps can connect to USB devices
 and read from and write to a user's serial ports.
 See also the reference docs for the
 <a href="experimental.usb.html">USB API</a>
 and the
-<a href="experimental.serial.html">Serial API</a>.
+<a href="serial.html">Serial API</a>.
 The <a href="experimental.bluetooth.html">Bluetooth API</a> has just landed and
 we'll write more on this soon.
 We've included a link to an early sample below.
 </p>
 
 <p class="note">
 <b>API Samples: </b>
 Want to play with the code?
 Check out the
 <a href="https://github.com/GoogleChrome/chrome-app-samples/tree/master/serial">serial</a>,
@@ skipping 666 matching lines @@
 You can flush your serial device buffer by issuing the flush command on the API:
 </p>
 
 <pre>
 var flushSerial=function(str) {
   chrome.experimental.serial.flush(connectionInfo.connectionId, onFlush);
 }
 </pre>
 
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