Fixes description grammar in a few places (#19607)

* Fixes punctuation on clown box description

* Fixes grammar in a couple places

code/game/objects/items/weapons/storage/boxes.dm

@@ -829,7 +829,7 @@
 
 /obj/item/storage/box/clown
 	name = "clown box"
-	desc = "A colorful cardboard box for the clown"
+	desc = "A colorful cardboard box for the clown."
 	icon_state = "box_clown"
 	var/robot_arm // This exists for bot construction
 

code/game/objects/structures/watercloset.dm

@@ -444,7 +444,7 @@
 
 /obj/item/bikehorn/rubberducky/captainducky
 	name = "captain rubber ducky"
-	desc = "Captain favorite rubber ducky. This one squeaks with power."
+	desc = "Captain's favorite rubber ducky. This one squeaks with power."
 	icon_state = "cap_rubber_ducky"
 
 /obj/structure/sink