Update README.md to reflect version changes (#432)

Author: Evan Savage

README.md

@@ -18,10 +18,10 @@
 <h2 align="center">Install</h2>
 
 ```bash
-# for webpack 1
-npm install --save-dev extract-text-webpack-plugin
 # for webpack 2
-npm install --save-dev extract-text-webpack-plugin@beta
+npm install --save-dev extract-text-webpack-plugin
+# for webpack 1
+npm install --save-dev extract-text-webpack-plugin@1.0.1
 ```
 
 <h2 align="center">Usage</h2>