Maybe add a Discord invite link to the "Help" menu

[Masterjun3]

The TASVideos.org Official Discord Server recently got its own #bizhawk channel. And currently, two options in the "Help" menu already link to the Bizhawk wiki page on TASVideos and to the BizHawk subforum on the TASVideos forum.

So I had the idea that maybe a third link, a Discord invite link, would fit there, since the current chat trend seems to be Discord. It seems Discord even has the ability to make an invite to a specific channel instead of the entire server, so that following the link directly opens the channel.

Just an idea I had. (And while making this issue ticket on this github I noticed there are a few links to the IRC channel, maybe that's the preferred chat? Maybe that should be the link, or even a fourth link, or none at all, I don't know.)