Documentation: net/mlx5: Wrap notes in admonition blocks

Wrap note paragraphs in note:: directive as it better fit for the
purpose of noting devlink commands.

Fixes: f2d51e57 ("net/mlx5: Separate mlx5 driver documentation into multiple pages")
Fixes: cf14af14

 ("net/mlx5e: Add vnic devlink health reporter to representors")
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>