update readme

- add installation notes for NPM and Yarn.
- add note about Bower's current development state
- update JQuery version

Author: browner12

README.md

@@ -6,14 +6,32 @@ Simple parallax scrolling effect inspired by [Spotify.com](http://spotify.com/)
 
 ## Installation
 
-Download package or install with Bower and include `parallax.min.js` in your document after including jQuery.
+### NPM
+
+```bash
+npm i --save jquery-parallax.js
+```
+
+### Yarn
+
+```bash
+yarn add jquery-parallax.js
+```
+
+### Bower
+
+Please note that although Bower is still maintained, they recommend Yarn for new projects.
 
 ```bash
 $ bower i --save parallax.js
 ```
 
+### Setup
+
+Include `parallax.min.js` in your document after including jQuery.
+
 ```html
-<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
+<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
 <script src="/path/to/parallax.min.js"></script>
 ```