[RM-21213] docs: update the changelog for 1.5.39
[RM-21213] docs: update the changelog for 1.5.39

Signed-off-by: Alfredo Deza <3f4d00ffa77e6441ab2d23c25a618925d2383b02@redhat.com>

ceph/ceph-deploy,ceph/ceph-deploy