Added development instructions to the README

Author: zeke

README.md

@@ -17,13 +17,23 @@ open swagger-ui-1.0/index.html
 How to Improve It
 -----------------
 
-1. [Fork!](https://github.com/wordnik/swagger-ui)
-1. Hack.
-1. Submit a pull request.
+First, create your own fork of [wordnik/swagger-ui](https://github.com/wordnik/swagger-ui)
 
-Note: The HTML and CSS are converted from Haml and Sass, which means there are currently some development 
-dependencies. We are looking into revamping the source files and eliminating all development 
-dependencies by using [less.js](http://lesscss.org/)
+To hack on swagger-ui, you'll need ruby. Then..
+
+```bash
+# Install the middleman gem:
+gem install middleman
+
+# Start up a development server on http://localhost:4567
+middleman
+
+# Edit the files in `/source`
+# Then when you're ready to build, run:
+middleman build
+```
+
+To share your changes, [submit a pull request](https://github.com/wordnik/swagger-ui/pull/new/master).
 
 License
 -------