fix typos in Voice.md

[jonobarel]

move question mark from the wrong column.

[lukellmann]

This seems to be at least partially wrong for request_to_speak_timestamp: we received the following JSON:

"voice_states": [
  {
    "user_id": "...",
    "suppress": false,
    "session_id": "...",
    "self_video": false,
    "self_mute": true,
    "self_deaf": false,
    "request_to_speak_timestamp": null,
    "mute": false,
    "deaf": false,
    "channel_id": "..."
  }
],

So I can confirm that request_to_speak_timestamp is nullable, I don't know if it is actually optional.

I can neither confirm nor deny that channel_id is optional or nullable.

[lukellmann]

Don't get me wrong, I don't want to insinuate anything, but were you aware of what the question marks stand for @jonobarel? (The title and the description could indicate that you weren't, since they don't mention anything about optional or nullable.)

Here is what they stand for:
https://discord.com/developers/docs/reference#nullable-and-optional-resource-fields

[jonobarel]

@lukellmann Actually I was not aware. I tried to look for it in the documentation and didn't find it so I guess that one's on me :)
Thanks for clarifying!