Lizardmen Temple Guard: One per Slann?

[rythos42]

The roster files claim that you need may include one Temple Guard unit per Slann in the army. The rulebook doesn't have this rule - I believe it was a rule from the last edition of the army book .

Also - if the Slann is in the army, the unit is Stubborn (noted in the files) and Immune to Psychology (not noted).

Thanks!