Missing Docker installation instructions

[slifty]

Describe the issue

The root README.md references docker installation instructions, but the install docs README.md doesn't clearly direct potential uses to where that documentation exists.

It might be good to either remove the reference to docker in the initial description, add a section for docker, or include the word docker in one of the three existing sections if that is where it exists (note: I see docker is used inside of the Tanka instructions, but that felt like it was a substep for a different installation stack, rather than docker being the primary installation vector)

Screenshots

Root README

Installation README

[stale]

This issue has been automatically marked as stale because it has not had any activity in the past 30 days. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[rfratto]

Reopening since there's an open PR to fix this.