feature: Github Action for CI and Deploy to GH Pages on push to master

[barakplasma]

Adds a Github Action which builds, and deploys to github pages.
to support this, you'll have to add two secrets to the project:

1. secrets.email with your email address
2. secrets.ACCESS_TOKEN with a github personal access token with only public_repo scope

Results in a github pages static site of the storybook. See https://barakplasma.github.io/addon-smart-knobs/ as an example. However, if merged to master, then the URL will be https://storybookjs.github.io/addon-smart-knobs/ instead.

replaces #57

[ndelangen]

@barakplasma https://github.com/storybookjs/addon-smart-knobs/invitations