docs(tutorial/step-07): fix typo in route pattern

One instance of `/phones/:phoneId` erroneously had a singular version,
`/phone/:phoneId`, which does not match what was actually used in the code.

Closes angular#7313

Author: jamiekrug

docs/content/tutorial/step_07.ngdoc

@@ -247,7 +247,7 @@ Our application routes are defined as follows:
   controller.
 
 * `when('/phones/:phoneId')`: The phone details view will be shown when the URL hash fragment
-  matches '/phone/:phoneId', where `:phoneId` is a variable part of the URL. To construct the phone
+  matches '/phones/:phoneId', where `:phoneId` is a variable part of the URL. To construct the phone
   details view, Angular will use the `phone-detail.html` template and the `PhoneDetailCtrl`
   controller.