[Users] avoid debug messages or explain better how to change log level

[Gianluca Cecchi]

Hello,
I remember many months ago a thread where someone complained about too
verbose logging.
Still today in 3.3.1 we have many many DEBUG messages in both vdsm and
engine logs.
Is there already a wiki explaining how to relax logging level?
I think that if we think it is now able to be production ready, this
implies changing default log level.
Right today it is difficult to understand logs because of verbosity,
in my opinion.
Best if in upcoming 3.3.2 release this could take place.
Anyway someone could always leverage the level as he/she needs...

What do you think about it?

Gianluca