Update internals.rst

redstar504 · weaverryan · commit b59a531e95a3 · 2014-07-28T06:41:14.000-05:00
The proper idiom is "behind the scenes".

I also fixed the sentence structure.
diff --git a/book/internals.rst b/book/internals.rst
@@ -10,8 +10,8 @@ Symfony2 internals.
 
 .. note::
 
-    You need to read this section only if you want to understand how Symfony2
-    works behind the scene, or if you want to extend Symfony2.
+    You only need to read this section if you want to understand how Symfony2
+    works behind the scenes, or if you want to extend Symfony2.
 
 Overview
 --------
