add support page

[beatgammit]

The link for Support goes nowhere, but it should list the preferred communication channels. Ideally there would be some kind of chat room (Matrix?), and a note about GitHub issue etiquette.

I understand that Iroh is under heavy development, so perhaps the support page should simply state that support will be coming soon. But not having any support page whatsoever is a bit discouraging (I wasn't sure if the page was just busted).

[b5]

Thank you for taking the time to file this issue @beatgammit. I'm sure numerous other folks had the same question, but didn't bother to say anything. I'll improve this & get back to you