feat(maps): adds koth_borgville_b4a1

Author: sonikro

maps.json

@@ -117,6 +117,10 @@
         "name": "koth_berry_b3a",
         "url": "https://tf2maps.net/downloads/borgville.19389/download"
     },
+    {
+        "name": "koth_borgville_b4a1",
+        "url": "https://tf2maps.net/downloads/borgville.19389/download"
+    },
     {
         "name": "arenares_well_rc2b",
         "url": "https://tf2maps.net/downloads/arena-respawn-well.19729/download"