Updating blog post about RTL from setAllowRTL to allowRTL (Android).

Summary:
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Updating blog post about RTL to use updated function `sharedI18nUtilInstance.allowRTL` for Android as mentioned in [this issue](https://github.com/facebook/react-native/issues/16166)

Check [this blog post](https://facebook.github.io/react-native/blog/2016/08/19/right-to-left-support-for-react-native-apps.html).
Closes https://github.com/facebook/react-native/pull/16184

Differential Revision: D5987016

Pulled By: hramos

fbshipit-source-id: 96eb066e0326a550e84d290dc1397fdc2ca5c4f4

blog/2016-08-19-right-to-left-support-for-react-native-apps.md

@@ -57,7 +57,7 @@ With this update, when you allow RTL layout for your app:
     ```java
     // in MainActivity.java
   	I18nUtil sharedI18nUtilInstance = I18nUtil.getInstance();
-  	sharedI18nUtilInstance.setAllowRTL(context, true);
+  	sharedI18nUtilInstance.allowRTL(context, true);
     ```
 
 3. For Android, you need add `android:supportsRtl="true"` to the [`<application>`](http://developer.android.com/guide/topics/manifest/application-element.html) element in `AndroidManifest.xml` file.