docs: logging: Replace example by link to kbase/debuglogs.html
docs: logging: Replace example by link to kbase/debuglogs.html

The 'debuglogs' knowledge base page has way more info and examples on
how to set logging use it instead of the ad-hoc examples.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Erik Skultety <2c14d38fa47c8799f1b9c16280abe27f8edfec6e@redhat.com>

zippy2/libvirt,zippy2/libvirt,crobinso/libvirt,jfehlig/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,libvirt/libvirt,olafhering/libvirt,olafhering/libvirt,libvirt/libvirt,jfehlig/libvirt,crobinso/libvirt,crobinso/libvirt,crobinso/libvirt,olafhering/libvirt,libvirt/libvirt,zippy2/libvirt,jfehlig/libvirt,zippy2/libvirt