docs: kbase: Port 'debuglogs' document from libvirt's wiki

docs: kbase: Port 'debuglogs' document from libvirt's wiki

Provide debug log configuration insight in our kbase.

There are two modifications of the document compared to the wiki
version:

1) The link for reporting a bug agains libvirt was modified to use the
   gitlab issue tracker.

2) The link to URI specification details is changed to 'https' protocol.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>