Update CONTRIBUTING.md

Author: zpao

CONTRIBUTING.md

@@ -48,7 +48,9 @@ Facebook has a [bounty program](https://www.facebook.com/whitehat/) for the safe
 * IRC - [#reactjs on freenode](http://webchat.freenode.net/?channels=reactjs)
 * Mailing list - [reactjs on Google Groups](http://groups.google.com/group/reactjs)
 
-## Coding Style
+## Style Guide
+
+### Code
 
 * Use semicolons;
 * Commas last,
@@ -59,6 +61,10 @@ Facebook has a [bounty program](https://www.facebook.com/whitehat/) for the safe
 * "Attractive"
 * Do not use the optional parameters of `setTimeout` and `setInterval`
 
+### Documentation
+
+* Do not wrap lines at 80 characters
+
 ## License
 
 By contributing to React, you agree that your contributions will be licensed under the [Apache License Version 2.0 (APLv2)](LICENSE).