chore: add contributing.md #8

Author: jonatansalas

CONTRIBUTING.md

@@ -0,0 +1,5 @@
+# Contributing to Styled-Animation
+
+1. [Fork](https://help.github.com/articles/fork-a-repo/) this repository to your own GitHub account and then [clone](https://help.github.com/articles/cloning-a-repository/) it to your local device.
+1. Install the dependencies: `npm i`.
+1. Run `npm run storybook` to run the stories behing `/stories` folder.