change usage to mixed fighter

data/core/units/orcs/Assassin.cfg

@@ -18,7 +18,7 @@
     alignment=chaotic
     advances_to=Orcish Slayer
     cost=17
-    usage=fighter
+    usage=mixed fighter
     description= _ "Though some consider it cowardly to use, poison is a weapon favored by orcs, especially those weak of frame. Orcish assassins, who use it on throwing knives, are typically frail by orcish standards, although surprisingly nimble. Though rarely the ones who deal the killing blow, their tactics are a considerable aid to their larger and more brutal kin."+{SPECIAL_NOTES}+{SPECIAL_NOTES_POISON}
     die_sound={SOUND_LIST:ORC_SMALL_DIE}
     [death]

data/core/units/orcs/Slayer.cfg

@@ -18,7 +18,7 @@
     advances_to=null
     {AMLA_DEFAULT}
     cost=33
-    usage=fighter
+    usage=mixed fighter
     description= _ "The larger or more skilled orcish assassins are called 'Slayers' by their enemies. Slayers are fast on their feet, and quite nimble in combat, although they achieve that end by forgoing armor. Their weapon of choice, poison, is a vicious tool, and its common use on the battlefield is often the real cause of orcish supremacy."+{SPECIAL_NOTES}+{SPECIAL_NOTES_POISON}
     die_sound={SOUND_LIST:ORC_DIE}
     {DEFENSE_ANIM "units/orcs/slayer-defend.png" "units/orcs/slayer.png" {SOUND_LIST:ORC_HIT} }