Fix docs URL in systemd service file.
Fix docs URL in systemd service file.

Fixes #13799.

Signed-off-by: Eric-Olivier Lamey <f4c975cbf19a2f6bc99185e7104594eb2d1a3102@lamey.me>
(cherry picked from commit dbf5e36fd6257ed237f76a65ccbae4124a4f0bdf)

AdamOssenford/docker-pi,AdamOssenford/docker-pi,AdamOssenford/docker-pi