Improve update process for NK Start

[szszszsz]

Add improvements from the #48 case.
Tasks:

• document potential issues when using Docker
• discuss Pip installation alternatives, e.g. using single Python bundled binary, or pipenv, or venv, etc.
• ask users to rerun the update process if the bootloader cannot be found
• document OpenOCD flashing on Arch Linux (see Nitrokey Start Update Went Badly - Critical error occurred, exiting now #48 last comments)
• run factory reset over ccid

[dragon788]

This could also potentially happen if trying to update/interact with Nitrokey devices from Crostini (Linux apps) on a Chromebook. You don't get direct access to the device as there is a "broker" process that you have to grant explicit permission to redirect the USB device into the Linux apps, and I have noticed in the past when trying to "switch identities" that nitropy fails because the device isn't immediately available until the user allows it again, and the "soft reset" that nitropy tries to do doesn't appear to have any effect from the Crostini environment.