Update MicrosoftMapping.json

PublicFeeds/ThreatActorNaming/MicrosoftMapping.json

@@ -3,7 +3,7 @@
         "Previous name": "ACTINIUM",
         "New name": "Aqua Blizzard",
         "Origin/Threat": "Russia",
-        "Other names": "UNC530, Primitive Bear, Gamaredon"
+        "Other names": ["UNC530", "Primitive Bear", "Gamaredon"]
     },
     {
         "Previous name": "AMERICIUM",