Remove unused flag from readme

Author: Pokom

README.md

@@ -89,7 +89,6 @@ If you are still using the legacy [Access scopes][access-scopes], the `https://w
 | `monitoring.aggregate-deltas` | No       |                           | If enabled will treat all DELTA metrics as an in-memory counter instead of a gauge. Be sure to read [what to know about aggregating DELTA metrics](#what-to-know-about-aggregating-delta-metrics) |
 | `monitoring.aggregate-deltas-ttl` | No       | `30m`                     | How long should a delta metric continue to be exported and stored after GCP stops producing it. Read [slow moving metrics](#slow-moving-metrics) to understand the problem this attempts to solve |
 | `monitoring.descriptor-cache-ttl` | No       | `0s`                      | How long should the metric descriptors for a prefixed be cached for                                                                                                                              |
-| `monitoring.enable-promhttp-custom-logger`                 | No       | False                     | If enabled will create a custom error logging handler for promhttp                                                                                                                               |
 | `stackdriver.max-retries`     | No       | `0`                       | Max number of retries that should be attempted on 503 errors from stackdriver.                                                                                                                   |
 | `stackdriver.http-timeout`    | No       | `10s`                     | How long should stackdriver_exporter wait for a result from the Stackdriver API.                                                                                                                 |
 | `stackdriver.max-backoff=`    | No       |                           | Max time between each request in an exp backoff scenario.                                                                                                                                        |