docs: improve Autoprefixer installation notice in README

README.md

@@ -42,19 +42,21 @@ Then to build with **Sass** ([Autoprefixer](https://github.com/postcss/autoprefi
 @include motion-ui-animations;
 ```
 
-Or to get the equivalent pre-compiled classes, import the Motion UI standalone **CSS** file `dist/motion-ui.css` or `dist/motion-ui.min.css`.
+> Autoprefixer is required for the Sass installation as Motion UI uses unprefixed transition and animation properties. We recommend you to install [PostCSS and Autoprefixer](https://github.com/postcss/autoprefixer).
+
+Or to use the equivalent pre-compiled **CSS**, import the Motion UI standalone CSS file `dist/motion-ui.css` or `dist/motion-ui.min.css`.
 
 To easily transition elements in and out using Motion UI classes, import the Motion UI **JavaScript** library `dist/motion-ui.js` or `dist/motion-ui.min.js`.
 
-See full [installation instructions](docs/installation.md)
+See the [full installation instructions](https://github.com/zurb/motion-ui/tree/master/docs/installation.md)
 
 ## Demos
 
 [View live demos on the ZURB Playground.](http://zurb.com/playground/motion-ui)
 
 ## Documentation
 
-[View the documentation here.](docs)
+[View the documentation here.](https://github.com/zurb/motion-ui/tree/master/docs)
 
 ## Develop Locally