Fix typo-ed "of"

sophiebits · sophiebits · commit d5b409002b42 · 2014-07-13T13:11:00.000-07:00
(cherry picked from commit 65b2232)
diff --git a/docs/_posts/2014-07-13-react-v0.11-rc1.md b/docs/_posts/2014-07-13-react-v0.11-rc1.md
@@ -122,8 +122,8 @@ Keyboard and mouse events also now include a normalized `e.getModifierState()` t
 * Added explicit warning when missing polyfills
 
 ### React With Addons
-* PureRenderMixin:
-* Perf: a new set off tools to help with performance analysis
+* PureRenderMixin
+* Perf: a new set of tools to help with performance analysis
 * Update: New `$apply` command to transform values
 * TransitionGroup bug fixes with null elements, Android
 
