Added stylesheet import

Author: rgabs

8-styling/8.3-separating-styles-from-component.md

@@ -63,6 +63,8 @@ export default Button;
 
 >Button.component.style.js
 ```js
+import { StyleSheet } from 'react-native';
+
 export default StyleSheet.create({
   container: {
     padding: 10,