Update README.md

wkh237 · web-flow · commit 17d9bbdb2a50 · 2016-07-23T17:05:03.000+08:00
diff --git a/README.md b/README.md
@@ -50,6 +50,8 @@ To upgrade your project
 $ react-native upgrade
 ```
 
+you will need run `rnpm link` again after upgrade.
+
 
 ### Manually link the package (Android)
 
