Fix typo (#520)

Author: 1rahul1

README.md

@@ -8,7 +8,7 @@
 
 This is a standalone app for debugging React Native apps:
 
-- Based on official [Remote Debugger](https://facebook.github.io/react-native/docs/debugging.html#chrome-developer-tools) and provide more functionally.
+- Based on official [Remote Debugger](https://facebook.github.io/react-native/docs/debugging.html#chrome-developer-tools) and provide more functionality.
 - Includes [React Inspector](docs/react-devtools-integration.md) from [`react-devtools-core`](https://github.com/facebook/react/tree/master/packages/react-devtools-core).
 - Includes Redux DevTools, made [the same API](docs/redux-devtools-integration.md) with [`redux-devtools-extension`](https://github.com/zalmoxisus/redux-devtools-extension).