Add `Developing` in README
Reusable [React] components and design elements that adhere to the Jenkins Design Language (Blue Ocean edition).
+## Developing
+```
+npm install
+npm run gulp
+npm run build-storybook
+npm run site-server
+```
+
> License is MIT. Other licenses in /licenses
__[Docs Site](http://jenkinsci.github.io/jenkins-design-language/docs)__
\ No newline at end of file
