mod_rest/apidemo: Serve yaml with a (non-standard) content-type There's no Standard from what I can tell, found this one somewhere. Serving as text/* might help some clients do something sensible like not treat it as a binary file, which it isn't.

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summary: Remote Roster Management
...

Introduction
============

This module adds support for [XEP-0321: Remote Roster Management] which
is commonly used to allow components such as transports to modify the
rosters of local users.