Update realm-app.txt (#528)

Author: nathan-contino-mongo

source/tutorial/realm-app.txt

@@ -279,12 +279,12 @@ line tool:
    the contents of that directory to create your very own Task Tracker
    {+app+} backend with the Realm CLI.
 
-#. Navigate to the ``tasktracker`` directory in the
+#. Navigate into the root directory of the
    ``realm-tutorial-backend`` project:
 
    .. code-block:: console
 
-      cd realm-tutorial-backend/tasktracker/
+      cd realm-tutorial-backend
 
 #. Run the ``import`` command of ``realm-cli`` to create your
    app.