Fix 2nd typo "effiecient" --> "efficient".

README.md

@@ -38,7 +38,7 @@ A project committed to make file acess and data transfer easier, efficient for R
 
 ## About
 
-This project was initially for solving the issue [facebook/react-native#854](https://github.com/facebook/react-native/issues/854), because React Native lack of `Blob` implementation and it will cause some problem when transfering binary data. Now, this project is committed to make file access and transfer more easier, effiecient for React Native developers. We've implemented highly customizable filesystem and network module which plays well together. For example, upload and download data directly from/to storage which is much more efficient in some cases(especially for large ones). The file system supports file stream, so you don't have to worry about OOM problem when accessing large files.
+This project was initially for solving the issue [facebook/react-native#854](https://github.com/facebook/react-native/issues/854), because React Native lack of `Blob` implementation and it will cause some problem when transfering binary data. Now, this project is committed to make file access and transfer more easier, efficient for React Native developers. We've implemented highly customizable filesystem and network module which plays well together. For example, upload and download data directly from/to storage which is much more efficient in some cases(especially for large ones). The file system supports file stream, so you don't have to worry about OOM problem when accessing large files.
 
 In `0.8.0` we introduced experimential Web API polyfills that make it possible to use browser-based libraries in React Native, for example, [FireBase JS SDK](https://github.com/wkh237/rn-firebase-storage-upload-sample)