Extend ChainTransactionInfoResponse object definition

[buberdds]

Would it be possible to represent ChainTransactionInfoResponse method https://github.com/bitcat365/oasisscan-backend/blob/master/api/api.json#L1983 as enum instead of string ?

      "method": {
        "type": "string",
        "enum": [
          "staking.Transfer",
          "staking.AddEscrow"
          ...whatever Oasis Scan can have here 
        ]
      }