feat(magic-items): Add first magic item image (#636)

src/5e-SRD-Magic-Items.json

@@ -51,6 +51,7 @@
       "Weapon (any ammunition), uncommon (+1), rare (+2), or very rare (+3)",
       "You have a bonus to attack and damage rolls made with this piece of magic ammunition. The bonus is determined by the rarity of the ammunition. Once it hits a target, the ammunition is no longer magical."
     ],
+    "image": "/api/images/magic-items/adamantine-armor.png",
     "url": "/api/magic-items/ammunition"
   },
   {