Remove info box about other versions as it always gets outdated

(cherry picked from commit 916ad43e52)

index.rst

@@ -7,12 +7,6 @@ Godot Docs – *3.3* branch
             Expand the "Read the Docs" panel at the bottom of the sidebar to see
             the list.
 
-  .. tip:: This is the documentation for the stable 3.3 branch.
-           Looking for the documentation of the current **development** branch?
-           `Have a look here <https://docs.godotengine.org/en/latest>`_.
-           You can also browse the documentation for the previous stable
-           `3.2 <https://docs.godotengine.org/en/3.2>`_ branch.
-
 .. only:: i18n
 
   .. note:: This documentation is translated from the `original English one