docs: add explanation for onMaxRetryTimesExceeded

README.md

@@ -66,6 +66,7 @@ client
 | shouldResetTimeout | `Boolean` | false | Defines if the timeout should be reset between retries |
 | retryDelay | `Function` | `function noDelay() { return 0; }` | A callback to further control the delay in milliseconds between retried requests. By default there is no delay between retries. Another option is exponentialDelay ([Exponential Backoff](https://developers.google.com/analytics/devguides/reporting/core/v3/errors#backoff)). The function is passed `retryCount` and `error`. |
 | onRetry | `Function` | `function onRetry(retryCount, error, requestConfig) { return; }` | A callback to notify when a retry is about to occur. Useful for tracing and you can any async process for example refresh a token on 401. By default nothing will occur. The function is passed `retryCount`, `error`, and `requestConfig`. |
+| onMaxRetryTimesExceeded | `Function` | `function onMaxRetryTimesExceeded(error, retryCount) { return; }` | After all the retries are failed, this callback will be called with the last error before throwing the error. |
 
 ## Testing