Updating dox for mod_rest. Ideas expressed / clarified: 1) Making clear that mod_rest isn't to be installed under VirtualHosts AND as a component. 2) Understanding some of the implications of this choice: A) Changes to user authentication B) How it affects subdomains 3) More consistent use of domain names for clarity. 4) Using different heading sizes to show scope of section. Essentially, I added all the tidbits I had to clarify in getting this to work in my own example.

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summary: Advertise an external TURN service
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This module advertises STUN/TURN service to clients via XEP-0215 (it utilizes
mod_external_services to do so, which will be automatically loaded by this
module and must be available).

This module is included with Prosody 0.12 but made available here for older
versions.

Documentation is available on the [Prosody site][doc:modules:mod_turn_external].