Docs update: manual sharding

[jb3]

• Update documentation of manual sharding methods in Nostrum.Shard.Supervisor
• Create new advanced documentation page showing an example of a reconnection

[tignear]

The disconnect/1 function returns a sequence (seq). Since the shard cannot deliver events occurring after this seq, the consumer will not receive those events. Moreover, the gateway will not send events occurring before the seq. Additionally, the session ID will be invalidated upon the first reconnection attempt, making it impossible to resume with the same session ID (though it may be possible by sending requests simultaneously). Consequently, events will not be delivered twice.

And Discord guarantees(I'm not sure if this can be called a guarantee.) that the session can be restarted for a few minutes.

If you simply close the TCP connection or use a different close code, the session will remain active and timeout after a few minutes. This can be useful when you're Resuming the previous session.

https://discord.com/developers/docs/topics/gateway#disconnecting

[jchristgit]

Thanks!