var naming consistency

Author: scniro

README.md

@@ -25,7 +25,7 @@ import {UnControlled as CodeMirror} from 'react-codemirror2'
     theme: 'material',
     lineNumbers: true
   }}
-  onChange={(editor, metadata, value) => {
+  onChange={(editor, data, value) => {
   }}
 />
 ```
@@ -40,7 +40,7 @@ import {Controlled as CodeMirror} from 'react-codemirror2'
   onBeforeChange={(editor, data, value) => {
     this.setState({value});
   }}
-  onChange={(editor, metadata, value) => {
+  onChange={(editor, data, value) => {
   }}
 />
 ```
@@ -154,4 +154,4 @@ require('codemirror/mode/javascript/javascript');
 - `onUpdate(editor, event)` - *[update](https://codemirror.net/doc/manual.html#event_update)*
 - `onViewportChange(editor, from, to)` - *[viewportChange](https://codemirror.net/doc/manual.html#event_viewportChange)*
 
-[MIT](./LICENSE) © 2017 [scniro](https://github.com/scniro)
+[MIT](./LICENSE) © 2017 [scniro](https://github.com/scniro)