Update version

Improve command to empty `authorized_keys` file

Update version

Update version

Provide more information on SSH welcome screen

Fix use of tabs instead of spaces for indentation

Improve documentation

Improve style

Reference targets in Make messages via variables

Delete `git` user/group before recreating them

Add justification why SSHD is invoked as `root`

Reduce use of "magic numbers"

Make exec. shell explicit

Indicate Docker `HEALTHCHECK` capability explicitly

Fix Docker `HEALTHCHECK` + improve stream redirect