Fix syntax error in messages.json

Author: Sam Philip

messages.json

@@ -9,6 +9,6 @@
     "0.3.6": "messages/0.3.6.md",
     "0.3.7": "messages/0.3.7.md",
     "0.3.8": "messages/0.3.8.md",
-    "0.3.9": "messages/0.3.9.md"
+    "0.3.9": "messages/0.3.9.md",
     "0.4.0": "messages/0.4.0.md"
 }