Convert a Google Doc to Markdown or HTML with “Docs to Markdown”

Now this comes in handy:

Docs to Markdown (GD2md-html) converts Google Docs to simple, readable Markdown or HTML.

This add-on allows you to create documents using the excellent editing and collaborative features of Google Docs, but publish as Markdown or HTML that you can store as text files using a version-control system.

Docs to Markdown on GSuite Marketplace →
Docs to Markdown Docs (GitHub Wiki) →