Add Protobuf to Data Import docs

[mradamcox]

TL;DR: Is it possible for me to contribute to the GitBook documentation for WebGeoDa?

Hi! I'm working with the WebGeoDa codebase that was deployed for the Opioids Environment Policy Scan (OEPS) project, currently hosted at https://oeps.healthyregions.org. I really appreciate the detailed documentation you've made for WebGeoDa Scaffolding, and was wondering if/how I can contribute to it.

The OEPS project uses a few external vector tilesets that are stored in Mapbox, which I assume is the Protobuf capability described at the bottom of this page. I would be happy to add content to fill the advanced docs gaps (to the best of my abilities), as the current link on that page is broken--seems like the nofurtherinformation/webgeoda-gitbook repo has been removed.

Thank you!