Add option + documentation to directly flash Switchbot->Tasmota without Middleware

[kendallgoto]

As per #22 - an open issue to provide documentation and a flashing mechanism to bypass the middleware firmware altogether in SwitchbOTA, and outline the pros/cons associated with this strategy.

Long term, this is likely an option that we can provide but shouldn't necessarily encourage, since it does have detrimental effects within Tasmota. However, for some users, it may be a safer approach for device flashing.