Update scenes_and_nodes.rst (#2471)

* Update scenes_and_nodes.rst

I came across an issue while following it, where when running a scene the window would be a ghost, unclickable, with no explanation.  Since many people use high density displays, it's worth noting!

* Update getting_started/step_by_step/scenes_and_nodes.rst

Co-Authored-By: Hugo Locurcio <[email protected]>

getting_started/step_by_step/scenes_and_nodes.rst

@@ -162,6 +162,13 @@ demo should finally execute:
 
 Success!
 
+.. note::
+
+    If this doesn't immediately work and you have a hiDPI display on
+    at least one of your monitors, go to
+    **Project → Project Settings → Display → Window** then enable
+    **Allow Hidpi** under **Dpi**.
+
 .. _doc_scenes_and_nodes-configuring_the_project:
 
 Configuring the project