Fix canvas_items stretch mode name in Multiple resolutions

Author: Calinou

tutorials/rendering/multiple_resolutions.rst

@@ -147,7 +147,7 @@ demonstrate the effect of different stretch modes. A single sprite, also
 
    .. image:: img/stretch_disabled_expand.gif
 
--  **Stretch Mode = 2D**: In this mode, the base size specified in
+-  **Stretch Mode = Canvas Items**: In this mode, the base size specified in
    width and height in the project settings is
    stretched to cover the whole screen (taking the **Stretch Aspect**
    setting into account). This means that everything is rendered