Write page "Configure WEBIRC"

[xPaw]

Would live at http://thelounge.chat/docs/guides/webirc

• See https://kiwiirc.com/docs/webirc
• See https://ircv3.net/specs/extensions/webirc.html
• Need to make clear that: 1) This needs collaborating with the IRC network; 2) config is per hostname
• You might not need it