Documentation phrase about panics in mpsc channel may be obsolete

[vi]

https://doc.rust-lang.org/std/sync/mpsc/fn.sync_channel.html#main

As with asynchronous channels, all senders will panic in send if the Receiver has been destroyed.

https://doc.rust-lang.org/std/sync/mpsc/struct.SyncSender.html#send.v

This function will never panic, but it may return Err if the Receiver has disconnected and is no longer able to receive information.

[Cobrand]

I will take care of this if no one minds