Fixed Remington ACR .223 description.

The description for the .223 variant of the ACR was that of the MK 18 CQBR. I swapped it with the one from it's .300 BLK counterpart, minus the .300 BLK specific part.

data/json/items/gun/223.json

@@ -477,7 +477,7 @@
       {
         "id": "acr",
         "name": { "str": "Remington ACR" },
-        "description": "This is a shorter M4 carbine with a 10.3 inch barrel, intended for confined spaces and close quarters battle situations."
+        "description": "This carbine was developed for military use in the early 21st century.  It is damaging and accurate, though its rate of fire is a bit slower than competing carbines."
       }
     ],
     "modes": [ [ "DEFAULT", "semi-auto", 1 ], [ "AUTO", "auto", 4 ] ]