[MIRROR] Grammar fixes to atom descriptions (#3165)

* Grammar fixes to atom descriptions

* compile errors

code/modules/atmospherics/machinery/components/unary_devices/heat_exchanger.dm

@@ -3,7 +3,7 @@
 	icon_state = "he_intact"
 
 	name = "heat exchanger"
-	desc = "Exchanges heat between two input gases. Setup for fast heat transfer"
+	desc = "Exchanges heat between two input gases. Set up for fast heat transfer."
 
 	can_unwrench = TRUE
 

code/modules/atmospherics/machinery/components/unary_devices/outlet_injector.dm

@@ -1,6 +1,6 @@
 /obj/machinery/atmospherics/components/unary/outlet_injector
 	name = "air injector"
-	desc = "Has a valve and pump attached to it"
+	desc = "Has a valve and pump attached to it."
 	icon_state = "inje_map"
 	use_power = IDLE_POWER_USE
 	can_unwrench = TRUE

code/modules/atmospherics/machinery/components/unary_devices/oxygen_generator.dm

@@ -3,7 +3,7 @@
 	icon_state = "o2gen_map"
 
 	name = "oxygen generator"
-	desc = "Generates oxygen"
+	desc = "Generates oxygen."
 
 	dir = SOUTH
 	initialize_directions = SOUTH