Documentation: add generic tips on how-to access and test for a SSH based device

[davidzwa]

I have multiple tips:

• flash the imager with a Raspberry Pi imager template (ensuring settings are saved for a next time you use the imager)
• clear your ssh known hosts file (or at least the lines that involve monsterpi) : it will or might block unknown ssh fingerprints, which is what happens with a fresh monsterpi install, since the SSH host fingerprint likely changes.
• (opinion) use MobaXTerm, or VSCode SSH but not Putty. Putty is a bit clunky imho.
• consider or try out RealVNC (its nice and free/freemium) alternative to ssh
• upgrade MonsterPi FDM Monster using the internal updater script
• use ping monsterpi.local to test the Pi to be up and running
• use a network scanner like Fing to detect up-and-running devices like a Raspberry Pi. Often it recognizes the Manufacturer of such devices and offers pinging on opened ports (like 80 or 4000)