Secure domain + Coturn - Need adapted instructions

[Commifreak]

Since I enabled LDAP auth, the TURN/TURNS did not work. I came across this post: https://community.jitsi.org/t/cant-get-jitsi-meet-to-work-with-turn-solved/32300/14?u=webcf and this did the trick.

This PR adds this information.

[jitsi-jenkins]

Hi, thanks for your contribution!
If you haven't already done so, could you please make sure you sign our CLA (https://jitsi.org/icla for individuals and https://jitsi.org/ccla for corporations)? We would unfortunately be unable to merge your patch unless we have that piece :(.

[Commifreak]

Hi, thanks for your contribution!
If you haven't already done so, could you please make sure you sign our CLA (https://jitsi.org/icla for individuals and https://jitsi.org/ccla for corporations)? We would unfortunately be unable to merge your patch unless we have that piece :(.

Done.

[damencho]

Can you slightly modify and make it more generic. Like: make sure you enable desired modules to the guest virtual host like turncredentials and conference_duration ...

[Commifreak]

Tried it.

But turncredetiansl should be enabled by default in the 1st example, since Jitsi installs coturn now by default, right?