Added a section on Scene loading

Added a section on loading/instancing and child-adding Scenes in GDScript since this is not covered by the Instancing tutorial (which only deals with the GUI way).

reference/gdscript.rst

@@ -929,6 +929,27 @@ illustration of this:
         self.myinteger=5
         print(self.myinteger)
 
+Loading Scenes
+~~~~~~~~~~~~~~
+
+A special case of resource-loading is when loading *Scenes*. Scenes are trees of nodes that form the basis of Godot's logical structure. Scenes are explained in more detail here: :ref:`doc_instancing`. A loaded scene resource must be *instantiated* into the current (running) scene tree before it can be used. This is done by calling its ``instance`` method:
+
+::
+
+   MyScene = preload("res://scenes/Myscene.tscn")
+   myscene = MyScene.instance()
+
+Calling ``.instance`` on the scene will trigger any ``_init`` constructors. The constructor doesn't take any arguments, so use a separate configuration function if some particular information should be passed to the instanced scene.
+
+It's important to note that in the example above, ``myscene`` is *not* yet added into the current scene tree - it works as a node without parent. This means, importantly, that any ``_ready`` function within ``myscene`` has not run, and no processing/fixed_processing can take place. If that is desired, ``myscene`` must be added as a child to a node within the running tree. For example, the ``add_child`` function adds ``myscene`` as a child to the current node: 
+
+::
+
+   add_child(myscene)
+
+
+
+
 Tool mode
 ~~~~~~~~~