docker: more and better

Author: jgvictores

docs/install-docker.md

@@ -6,6 +6,21 @@ We use [Docker](https://www.docker.com) for images and containers.
 
 Simply go to [Docker](https://www.docker.com) and download your version.
 
+## Install Docker (Ubuntu)
+
+```bash
+sudo apt install docker.io
+```
+
+Post-install, rather than rootless, prefer to (<https://docs.docker.com/engine/install/linux-postinstall/>):
+
+```bash
+sudo groupadd docker # may already exist
+sudo usermod -aG docker $USER
+```
+
+Then log out and in or simply `newgrp docker`.
+
 ## Additional Information
 
 ### Similar and related
@@ -18,6 +33,19 @@ Compose V2 is included with all currently supported versions of Docker Desktop.
 
 - [osrf/rocker](https://github.com/osrf/rocker): A tool to run docker containers with overlays and convenient options for things like GUIs etc.
 
+Can be installed via `pip`:
+
+```bash
+pip install rocker
+```
+
+But starting on Ubuntu 24.04:
+
+```bash
+pipx install rocker
+pipx ensurepath
+```
+
 ### Tutorials and Examples
 
 - <https://asrob.uc3m.es/tutoriales/software/docker.html>