Add VisualScript pending removal notice in Godot 4.0

tutorials/scripting/visual_script/index.rst

@@ -1,6 +1,16 @@
 VisualScript
 ============
 
+.. warning::
+
+    `Godot 4.0 will remove VisualScript from core entirely. <https://godotengine.org/article/godot-4-will-discontinue-visual-scripting>`__
+    As a result, creating new projects using visual scripting in Godot is not recommended.
+    Future Godot 4.x releases may have VisualScript reimplemented as an extension.
+
+    While Godot 3.x will keep VisualScript supported, we recommend
+    :ref:`trying out GDScript <toc-learn-scripting-gdscript>` instead,
+    especially if you intend to migrate your project to Godot 4.
+
 .. toctree::
    :maxdepth: 3
    :name: toc-learn-scripting-visual_script