doc: update docs

Author: wangdicoder

README.md

@@ -2,7 +2,7 @@
 
 ![npm](https://img.shields.io/npm/dy/react-native-progress-webview.svg) ![npm](https://img.shields.io/npm/v/react-native-progress-webview.svg) [![star this repo](http://githubbadges.com/star.svg?user=wangdicoder&repo=react-native-progress-webview&style=flat)](https://github.com/wangdicoder/react-native-progress-webview) ![GitHub](https://img.shields.io/github/license/wangdicoder/react-native-progress-webview.svg)
 
-**React Native Progress WebView** is a wrapper of [React Native WebView](https://github.com/react-native-community/react-native-webview) to provide the loading status.
+**React Native Progress WebView** is a wrapper of [React Native WebView](https://github.com/react-native-community/react-native-webview) to provide a loading bar on the top of the browser.
 
 <img src="https://raw.githubusercontent.com/wangdicoder/react-native-progress-webview/master/screenshot.gif" width="326" height="576" />
 
@@ -50,6 +50,34 @@ class App extends Component {
 | errorColor        | string | #f30    | the error color of loading bar                              |
 | disappearDuration | number | 300     | the visible duration after the webview finishes the loading |
 
+## Common issues
+
+#### How can I use `ref` to get WebView methods?
+
+It's same as using raw WebView. You can just pass a `ref` prop to get the instance.
+
+```jsx
+class App extends Component {
+  constructor(props){
+    super(props);
+    this.ref = React.createRef();
+  }
+
+  componentDidMount() {
+    console.log(this.ref.current);
+  }
+
+  render() {
+    return (
+      <ProgressWebView
+        ref={this.ref}
+        source={{ uri: 'https://facebook.github.io/react-native/' }} 
+      />
+    );
+  }
+}
+```
+
 ## License
 
 MIT

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-native-progress-webview",
-  "version": "1.1.1",
+  "version": "1.1.2",
   "description": "React Native Progress WebView is a wrapper of React Native WebView to provide the loading status.",
   "main": "index.js",
   "scripts": {