Update NetHSM CLI command options and messages

[mmerklinger]

This PR adjusts the documentation to recent changes in the pynitrokey NetHSM CLI.

PRs with the respective changes are:

• https://github.com/Nitrokey/pynitrokey/pull/469
• https://github.com/Nitrokey/pynitrokey/pull/476
• https://github.com/Nitrokey/pynitrokey/pull/477

[jans23]

Are the warnings in the code blocks sufficient or should we add an additional warning box?

[mmerklinger]

I added the warnings also in a warning box below the explanation of the command. Similar like with all the other warning boxes.