workshop template for DC-Economics

At present there is not a preconfigured workshop template for the Economics lesson for Data Carpentry.

As a workaround i rewrote the content for part of the social science workshop so that I could render the site in this repo

https://github.com/lachlandeer/2020-10-26-american-online-economics

I propose taking the reworked content from here and adding it as its own "if-else" options so that from `config.yml` instructors can get a preconfigured workshop template.