Merge pull request facebook#2211 from jacobgreenleaf/master

Fix typo in documentation in Flux Todo List

Author: zpao

docs/docs/flux-todo-list.md

@@ -349,6 +349,7 @@ At a high level, the React component hierarchy of the app looks like this:
         <TodoItem />
       </ul>
     </MainSection>
+  </Header>
 
 </TodoApp>
 ```