Update prefer-es6-class documentation

Author: yannickcr

README.md

@@ -129,7 +129,7 @@ Finally, enable all of the rules that you would like to use.
 * [no-multi-comp](docs/rules/no-multi-comp.md): Prevent multiple component definition per file
 * [no-set-state](docs/rules/no-set-state.md): Prevent usage of `setState`
 * [no-unknown-property](docs/rules/no-unknown-property.md): Prevent usage of unknown DOM property
-* [prefer-es6-class](docs/rules/prefer-es6-class.md): Prefer es6 class instead of createClass for React Components
+* [prefer-es6-class](docs/rules/prefer-es6-class.md): Enforce ES5 or ES6 class for React Components
 * [prop-types](docs/rules/prop-types.md): Prevent missing props validation in a React component definition
 * [react-in-jsx-scope](docs/rules/react-in-jsx-scope.md): Prevent missing `React` when using JSX
 * [require-extension](docs/rules/require-extension.md): Restrict file extensions that may be required

docs/rules/prefer-es6-class.md

@@ -1,27 +1,59 @@
-ES6 class bodies are more terse than traditional object literals. Methods do not require a `function` keyword and no commas are needed to separate them. This refactoring looks as such:
+# Enforce ES5 or ES6 class for React Components (prefer-es6-class)
 
-Invalid:
+React offers you two way to create traditional components: using the ES5 `React.createClass` method or the new ES6 class system. This rule allow you to enforce one way or another.
+
+## Rule Options
+
+```js
+...
+"prefer-es6-class": [<enabled>, <mode>]
+...
+```
+
+### `always` mode
+
+Will enforce ES6 classes for React Components. This is the default mode.
+
+The following patterns are considered warnings:
 
 ```js
-var ExampleComponent = React.createClass({
- render: function() { 
-  return <div onClick={this._handleClick}>Hello, world.</div>;
- },
- _handleClick: function() {
-  console.log(this);
- }
+var Hello = React.createClass({
+  render: function() {
+    return <div>Hello {this.props.name}</div>;
+  }
 });
 ```
 
-Valid:
+The following patterns are not considered warnings:
+
+```js
+class Hello extends React.Component {
+  render() {
+    return <div>Hello {this.props.name}</div>;
+  }
+}
+```
+
+### `never` mode
+
+Will enforce ES5 classes for React Components
+
+The following patterns are considered warnings:
 
 ```js
-class ExampleComponent extends React.Component {
- render() { 
-  return <div onClick={this._handleClick}>Hello, world.</div>;
- }
- _handleClick() {
-  console.log(this);
- }
+class Hello extends React.Component {
+  render() {
+    return <div>Hello {this.props.name}</div>;
+  }
 }
-```
+```
+
+The following patterns are not considered warnings:
+
+```js
+var Hello = React.createClass({
+  render: function() {
+    return <div>Hello {this.props.name}</div>;
+  }
+});
+```