Omit Juno release in Mellanox Neutron Plugin section

Mellanox Neutron Plugin has been deprecated in Juno

Change-Id: I75f5b3eceb393c8811eec08b6af388f422fa49c6
Signed-off-by: Omri Marcovitch <omrim@mellanox.com>
Merge "Omit Juno release in Mellanox Neutron Plugin section"