Doc: change filename and page name to match title

The Android app tutorial is now a more generic mobile app tutorial, so
it was moved to qtquick folder and renamed as creator-mobile-app-tutorial.qdoc.
The page name (HTML) was also changed accordingly.

Change-Id: I749f45a611b32204e5551884238f79d3d3b639fa
Reviewed-by: Sergio Ahumada <sahumada@blackberry.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
(cherry picked from commit 3e0ffdcba4)
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

doc/src/projects/creator-projects-overview.qdoc

@@ -24,7 +24,7 @@
 
 /*!
     \contentspage {Qt Creator Manual}
-    \previouspage creator-android-app-tutorial.html
+    \previouspage creator-mobile-app-tutorial.html
     \page creator-project-managing.html
     \nextpage creator-project-creating.html
 

doc/src/qtquick/creator-mobile-app-tutorial.qdoc

@@ -25,7 +25,7 @@
 /*!
     \contentspage {Qt Creator Manual}
     \previouspage creator-writing-program.html
-    \page creator-android-app-tutorial.html
+    \page creator-mobile-app-tutorial.html
     \nextpage creator-project-managing.html
 
     \title Creating a Mobile Application

doc/src/widgets/qtdesigner-app-tutorial.qdoc

@@ -26,7 +26,7 @@
     \contentspage {Qt Creator Manual}
     \previouspage creator-qml-application.html
     \page creator-writing-program.html
-    \nextpage creator-android-app-tutorial.html
+    \nextpage creator-mobile-app-tutorial.html
 
     \title Creating a Qt Widget Based Application