code: def update_external_store(self, project_name, config):
          
  
          headers = {"x-log-bodyrawsize": '0', "Content-Type": "application/json"}
          params = {}
          resource = "/externalstores/" + config.externalStoreName
          body_str = six.b(json.dumps(config.to_json()))
          (resp, header) = self._send("PUT", project_name, body_str, resource, params, headers)
          return UpdateExternalStoreResponse(header, resp)
docs: update the logstore meta info
          Unsuccessful opertaion will cause an LogException.
  
          :type config: ExternalStoreConfig
          :param config : external store config
  
          :return: UpdateExternalStoreResponse
          
          :raise: LogException