Questions about subprotocols crates

[plebhash]

this discussion should guide the documentation of subprotocols crates, as described on #845

[jbesraa]

https://stratumprotocol.org/specification/03-Protocol-Overview/#36-common-protocol-messages in here we have Reconnect message as part of the common messages protocol, but in the code Reconnect lives inside the mining messages crate.

Should probably be moved to common_messages_sv2 crate.