Update README.md

yuezk · yuezk · commit d268844d9d85 · 2017-05-07T19:45:44.000+08:00
diff --git a/README.md b/README.md
@@ -28,10 +28,18 @@
 
 ## Install
 
+For `postcss 6.x`:
+
 ```sh
 npm install postcss-filter-gradient --save-dev
 ```
 
+and for `postcss 5.x`
+
+```sh
+npm install postcss-filter-gradient@0.x --save-dev
+```
+
 ## Usage
 
 ```js
