Update docker-installation.md

[Leopere]

Modernized and Clarified docker-installation.md Removed superfluous steps and whitespace. Updated the docker compose to the modern docker compose plugin since docker-compose itself is likely to get deprecated and the docker compose plugin is baked into docker. Implemented headers in Markdown as that is more compatible with screen readers.

[Leopere]

I'm just doing a couple of hit and runs but I'm open to suggestions on how better to submit this.

[pateljannat]

This file is no longer being directly used.