chore(release): 6.3.0 [skip ci]

# [6.3.0](https://github.com/react-native-community/react-native-webview/compare/v6.2.3...v6.3.0) (2019-06-13)

### Features

* **iOS WKWebView:** Add mainDocumentURL to onShouldStartLoadWithRequest([#493](https://github.com/react-native-community/react-native-webview/issues/493)) ([71d1fcc](https://github.com/react-native-community/react-native-webview/commit/71d1fcc))

package.json

@@ -8,7 +8,7 @@
     "Thibault Malbranche <malbranche.thibault@gmail.com>"
   ],
   "license": "MIT",
-  "version": "6.2.3",
+  "version": "6.3.0",
   "homepage": "https://github.com/react-native-community/react-native-webview#readme",
   "scripts": {
     "ci": "CI=true && yarn lint && yarn test",