Install Discourse for development using Docker

I’m trying to use Docker on Windows 10, and I have a question about the guide. I have Docker installed and it can run an ubuntu container (with basically nothing installed in the container). This docker guide just says to clone the repo next, but I can’t do that since the container doesn’t have git installed.

At this point, should I just follow the Ubuntu Guide and install all of the prerequisites in the container? Or should I be using the discourse_dev image referenced on Github? It seems like this guide is skipping over a lot of steps, but I’ve never used docker before so maybe I’m missing something.