Merge pull request #100 from coryhouse/patch-1

Grammar fixes

Author: vasanthk

patterns/19.async-nature-of-setState.md

@@ -19,8 +19,8 @@ And that render was called immediately after triggering the setState method. But
 Well, it turns out React does not understand and thus cannot control code that doesn't live inside the library.
 Timeouts or AJAX calls for example, are developer authored code that executes outside of the context of React.
 
-So why does React synchronously updated the state in these cases? Well, because it's trying to be as defensive as possible.
-Not being in control means it's not able to do any perf optimisations so it's better to update the state on spot and
+So why does React synchronously update the state in these cases? Well, because it's trying to be as defensive as possible.
+Not being in control means it's not able to do any performance optimisations so it's better to update the state on spot and
 make sure the code that follows has access to the latest information available.
 
 ```javascript