Spell Benoit's name correctly. Add Changes section.

Author: tabatkins

css-will-change/Overview.bs

@@ -290,5 +290,11 @@ Hinting at Future Behavior: the 'will-change' property</h2>
 Acknowledgements {#acks}
 ========================
 
-Thanks to Benoit Gerard for originally suggesting the <css>will-animate</css> property,
+Thanks to Benoit Girard for originally suggesting the <css>will-animate</css> property,
 and doing a lot of the initial design work.
+
+Changes since the April 29 2014 Working Draft {#changes}
+========================================================
+
+* Added an explanatory section giving guidance on how to use 'will-change' well.
+* Specified the behavior of shorthands