make more snotes netwide

[edk0]

seven made a lot of server notices netwide, and I think most of those should be netwide for charybdis too—many of them are operationally relevant, and having to be connected to all the servers you operate starts feeling bad at about two servers. we probably need to be a little bit more careful about secrecy than seven was, for the sake of networks where servers have different admins, but most of them should be uncontentious

This brushes up against the politics of tradirc vs centrally-managed, but I'm hopeful that nobody will be too bothered by knowing when other servers unload modules.