Doc: Fix example path for Qt Quick scenegraph examples

Base path (examples/quick) is now defined in qdocconf file, example
docs need to adjust their paths for \example command.

Change-Id: I18412c4adf73691903ee58c9a056b6a4998d4d6a
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>

examples/quick/scenegraph/textureinsgnode/doc/src/textureinsgnode.qdoc

@@ -26,7 +26,7 @@
 ****************************************************************************/
 
 /*!
-    \example quick/scenegraph/textureinsgnode
+    \example scenegraph/textureinsgnode
     \title Scene Graph - Rendering FBOs
     \ingroup qtquickexamples
 

examples/quick/scenegraph/textureinthread/doc/src/textureinthread.qdoc

@@ -26,7 +26,7 @@
 ****************************************************************************/
 
 /*!
-    \example quick/scenegraph/textureinthread
+    \example scenegraph/textureinthread
     \title Scene Graph - Rendering FBOs in a thread
     \ingroup qtquickexamples