mod_pubsub_serverinfo: New module that uses pub/sub to make accessible server info This first implemetnation is laughably simple: it only adds a disco#info feature. This flags 'opt-in' for inclusion of local domain names in the data exposed by other domains (per the domain), which will allow servers to be listed in the XMPP Network Graph at https://xmppnetwork.goodbytes.im Hopefully, this bare-boned implementation acts as a stepping stone for future improvements.

This module helps make BOSH and WebSocket connection endpoints
discoverable via the HTTP method described in
[XEP-0156](https://xmpp.org/extensions/xep-0156.html#http).