Update hardware_communication.md with Stenograph USB format info from…

[ThaiWood]

… plugin docs

Summary of changes

This is the explanation of the protocol extracted from the stenograph_usb plugin, just with Mira replaced with writer since it applies to all of them.

Somewhere I have the doc where this was originally copied from and a draft of some extra abilities (e.g. packet IDs to do different things), but I figure this is a good start.

[mkrnr]

Thank you so much @ThaiWood for the contribution!

I'm wondering, however, whether we want to include this info in the plover documentation since it's regarding logic of a plugin and not plover itself. To me it feels more natural to link to the plugin documentation instead.

@sammdot what are your thoughts on this?

[sammdot]

Agree on this being included in the plugin documentation, at least for now. If we ever decide to bring this and other machine protocols into Plover's codebase then sure, but for right now I think keep it with the plugin.

[ThaiWood]

I think I'm missing something here. Is the disucssion to move this section or the hardware communication doc? If the former, what would go under the USB-based Protocols section if not things like the packet format of a USB protocol?

[mkrnr]

Sorry for the confusion! We should only include USB protocols in this documentation that are implemented in this repo which is not the case for stenograph.