mod_pubsub_serverinfo: Update to use mod_server_info (fixes #1841)
...but only for Prosody trunk users, because 0.12 mod_server_contact_info does
not use the new API in mod_server_info.
# Introduction
This module adds support for advertising the language used in a room.
# Configuring
``` {.lua}
Component "rooms.example.net" "muc"
modules_enabled = {
"muc_lang";
}
```
The room language is specified in a new field in the room configuration
dialog, accessible through compatible clients.
Use [language codes](https://en.wikipedia.org/wiki/ISO_639) like `en`,
`fr`, `de` etc.
# Compatibility
Meant for use with Prosody 0.10.x
Native support was [added in Prosody
trunk/0.11](https://hg.prosody.im/trunk/rev/9c90cd2fc4c3), so there is
no need for this module.