Add example in openapi description for delegations endpoint

endpoints/account-balances/get_account_delegations.sql

@@ -31,6 +31,11 @@ SET ROLE btracker_owner;
             schema:
               type: string
               x-sql-datatype: JSON
+            example: 
+              - {
+                  "outgoing_delegations": [],
+                  "incoming_delegations": []
+                }
       '404':
         description: No such account in the database
  */

endpoints/endpoint_schema.sql

@@ -494,7 +494,13 @@ declare
                 "schema": {
                   "type": "string",
                   "x-sql-datatype": "JSON"
-                }
+                },
+                "example": [
+                  {
+                    "outgoing_delegations": [],
+                    "incoming_delegations": []
+                  }
+                ]
               }
             }
           },