Link to "Domain for sale" url

[dewey]

The Link to bitchx.com on https://ircv3.net/participation is linking to a domain for sale page, looks like the domain is expired and not active any more.

[SadieCat]

I think BitchX is unmaintained so we should probably remove any references to it from the site.

[jwheare]

PR welcome :)

[jwheare]

FWIW BitchX does still have a repo that we link to on the clients page https://github.com/BitchX/BitchX1.3