fix example in json (#2547)

* fix example in json

example should be same level with schema

* Update versions/3.1.1.md

Co-authored-by: Mike Ralphson <[email protected]>

Co-authored-by: Mike Ralphson <[email protected]>

Author: jiangying000

versions/3.1.1.md

@@ -1793,9 +1793,9 @@ Plain text response with headers:
   "content": {
     "text/plain": {
       "schema": {
-        "type": "string",
-        "example": "whoa!"
-      }
+        "type": "string"
+      },
+      "example": "whoa!"
     }
   },
   "headers": {