Add a warning in the "Changing logging levels" documentation advising that it might hinder support in debugging issues

There has been some customers who follow the documentations in
https://developer.couchbase.com/documentation/server/3.x/admin/Misc/Trbl-logs.html#story-h2-3
Or https://developer.couchbase.com/documentation/server/current/clustersetup/ui-logs.html

to change the logging level in Couchbase Support. This might hinder the Support team from effectively debugging issues for that customer.

It would be good to add a warning advising against such practice for the above reason.