docs: add MonsterPi page with handy commands to be executed over SSH in certain situations

[davidzwa]

• sudo service fdmmonster restart restart the service
• sudo service fdmmonster stop stop the service
  or

• sudo systemctl restart fdmmonster.service use systemctl (older tool, same result)

# If you see multiple processes with the same name, you can collapse them with capital H
# If you see a CPU percentage above 100%, you can conclude that the process is very very busy 😉 
# If you see the VIRT exceeding multiple gigabytes, do not worry. It might be healthy to restart your Pi so the buffered/cached virtual RAM is cleared, but this does not mean your system is overloaded. The yellow Mem bar you should pay attention to.
htop

free -h

Add handy ways to update the daemon scripts.

Etc etc