Add link.

docs/docker-ubuntu.md

@@ -3,9 +3,10 @@
 > **Warning:** when using Ubuntu, for the tutorials, it is not recommended to run `apt get install docker` directly to
 > install Docker
 >
-> This is because the default Docker package associated with Ubuntu can be outdated and will install an obsolete Docker
-> version leading to issues with `docker` and `docker-compose` versions. Check you are using Docker version 24.0.x or
-> higher and Docker Compose 2.29.x or higher and upgrade if necessary.
+> This is because the default Docker package associated with Ubuntu can be
+> [outdated](https://askubuntu.com/questions/151283/why-dont-the-ubuntu-repositories-have-the-latest-versions-of-software)
+> and will install an obsolete Docker version leading to issues with `docker` and `docker-compose` versions. Check you
+> are using Docker version 24.0.x or higher and Docker Compose 2.29.x or higher and upgrade if necessary.
 
 Further details can be found under: `https://docs.docker.com/engine/install/ubuntu/#set-up-the-repository`