docs: update info about migrate command

Author: jamesgeorge007

.github/CONTRIBUTING.md

@@ -262,10 +262,8 @@ For more information about what each part of the template mean, head up to the d
 
 ## Migrate with the CLI
 
-This is a new feature in development for the CLI.
-
 ```sh
-webpack --migrate <your-config-name>
+webpack migrate
 ```
 
 The expected result of the above command is to take the mentioned `webpack` configuration and create a new configuration file which is compatible with webpack 2.
@@ -307,10 +305,10 @@ Each test will refer to an input webpack config snippet.
 Conventionally we write them in `\_\_testfixtures\_\_`.
 
 ```js
-const defineTest = require("../defineTest");
+const defineTest = require('../defineTest');
 
-defineTest(__dirname, "transform-name.input1.js");
-defineTest(__dirname, "transform-name.input2.js");
+defineTest(__dirname, 'transform-name.input1.js');
+defineTest(__dirname, 'transform-name.input2.js');
 ```
 
 `defineTest` is a helper test method which helps us to run tests on all the transforms uniformly.