fix: fix Message Trait example field (#85)

Author: char0n

schemas/2.1.0.json

@@ -934,7 +934,26 @@
         "examples": {
           "type": "array",
           "items": {
-            "type": "object"
+            "type": "object",
+            "additionalProperties": false,
+            "anyOf": [
+              {"required": ["payload"] },
+              {"required": ["headers"] }
+            ],
+            "properties": {
+              "name": {
+                "type": "string",
+                "description": "Machine readable name of the message example."
+              },
+              "summary": {
+                "type": "string",
+                "description": "A brief summary of the message example."
+              },
+              "headers": {
+                "type": "object"
+              },
+              "payload": {}
+            }
           }
         },
         "bindings": {