Add Stackbit

[budparr]

documented here:
https://github.com/JugglerX/hugo-serif-theme - Scroll down in the README and you can see the "create with stackbit" button. If possible we'd like to do the same for Ananke. So to do this you need to add a stackbit.yaml with some content models which I've documented here: https://docs.stackbit.com/uniform/

[susodapop]

This blog post should help: https://www.stackbit.com/blog/hugo-stackbit-tutorial/