Fix small typo in SceneTree docs

tutorials/step_by_step/scene_tree.rst

@@ -97,7 +97,7 @@ Scene tree
 When a node is connected, directly or indirectly, to the root
 viewport, it becomes part of the *scene tree*.
 
-This means that, as explained in previous tutorials, will get the
+This means that, as explained in previous tutorials, it will get the
 _enter_tree() and _ready() callbacks (as well as _exit_tree()).
 
 .. image:: /img/activescene.png