Moved app_hardware.html to app_usb.html. Will split out serial port

chrome/common/extensions/docs/templates/json/apps_sidenav.json

 [
   {
     "title": "Discover",
     "items": [
       {
         "title": "What Are Chrome Apps?",
         "href": "/apps/about_apps.html"
       }
     ]
   },
@@ skipping 157 matching lines @@
                 "href": "/apps/app_storage.html"
               }
             ]
           },
           {
             "title": "Use Low-Level System Services",
             "toggleable": true,
             "items": [
               {
                 "title": "USB",
-                "href": "/apps/app_hardware.html"
+                "href": "/apps/app_usb.html"
               },
               {
                 "title": "Network Communications",
                 "href": "/apps/app_network.html"
               }
             ]
           },
           {
             "title": "Interact with the Host Platform",
             "toggleable": true,
@@ skipping 76 matching lines @@
         "title": "Google Groups",
         "href": "https://groups.google.com/a/chromium.org/forum/#!forum/chromium-apps"
       },
       {
         "title": "Stack Overflow",
         "href": "http://stackoverflow.com/questions/tagged/google-chrome-app"
       }
     ]
   }
 ]