separate contribution rules from readme

CONTRIBUTING.md

@@ -0,0 +1,15 @@
+## Contributing
+
+Please keep the [issue tracker](http://github.com/hakimel/reveal.js/issues) limited to **bug reports**, **feature requests** and **pull requests**. If you are reporting a bug make sure to include information about which browser and operating system you are using as well as the necessary steps to reproduce the issue.
+
+If you have personal support questions use [StackOverflow](http://stackoverflow.com/questions/tagged/reveal.js).
+
+
+### Pull requests
+
+- Should follow the coding style of the file you work in, most importantly:
+  - Tabs to indent
+  - Single-quoted strings
+- Should be made towards the **dev branch**
+- Should be submitted from a feature/topic branch (not your master)
+- Should not include the minified **reveal.min.js** or **reveal.min.css** files

README.md

@@ -909,23 +909,6 @@ You can change the port by using `grunt serve --port 8001`.
 - **lib/** All other third party assets (JavaScript, CSS, fonts)
 
 
-### Contributing
-
-Please keep the [issue tracker](http://github.com/hakimel/reveal.js/issues) limited to **bug reports**, **feature requests** and **pull requests**. If you are reporting a bug make sure to include information about which browser and operating system you are using as well as the necessary steps to reproduce the issue.
-
-If you have personal support questions use [StackOverflow](http://stackoverflow.com/questions/tagged/reveal.js).
-
-
-#### Pull requests
-
-- Should follow the coding style of the file you work in, most importantly:
-  - Tabs to indent
-  - Single-quoted strings
-- Should be made towards the **dev branch**
-- Should be submitted from a feature/topic branch (not your master)
-- Should not include the minified **reveal.min.js** or **reveal.min.css** files
-
-
 ## License
 
 MIT licensed