Updates README

Adds note regarding adding tests to new features

Author: jameshamann

README.md

@@ -229,7 +229,7 @@ Bug reports and pull requests are welcome on GitHub at https://github.com/jamesh
 
 ## Development
 
-To set up your environment to develop and further customise this theme, fork the repo and explore the ```_assets``` directory, which includes all the ```css, js``` and ```font``` folders.
+To set up your environment to develop and further customise this theme, fork the repo and explore the ```_assets``` directory, which includes all the ```css, js``` and ```font``` folders. If you're adding a feature, please add some tests in the ```spec``` directory to ensure everyhting works as intended. 
 
 ## Contributors