Update README to also set ECS_ENABLE_UNTRACKED_IMAGE_CLEANUP when using NON_ECS_IMAGE_MINIMUM_CLEANUP_AGE

Author: mye956

README.md

@@ -205,7 +205,7 @@ additional details about how to configure the agent.
 | `ECS_DISABLE_IMAGE_CLEANUP` | `true` | Whether to disable automated image cleanup for the ECS Agent. | `false` | `false` |
 | `ECS_IMAGE_CLEANUP_INTERVAL` | 30m | The time interval between automated image cleanup cycles. If set to less than 10 minutes, the value is ignored. | 30m | 30m |
 | `ECS_IMAGE_MINIMUM_CLEANUP_AGE` | 30m | The minimum time interval between when an image is pulled and when it can be considered for automated image cleanup. | 1h | 1h |
-| `NON_ECS_IMAGE_MINIMUM_CLEANUP_AGE` | 30m | The minimum time interval between when a non ECS image is created and when it can be considered for automated image cleanup. | 1h | 1h |
+| `NON_ECS_IMAGE_MINIMUM_CLEANUP_AGE` | 30m | The minimum time interval between when a non ECS image is created and when it can be considered for automated image cleanup. You will need to also set `ECS_ENABLE_UNTRACKED_IMAGE_CLEANUP` to `true`. | 1h | 1h |
 | `ECS_NUM_IMAGES_DELETE_PER_CYCLE` | 5 | The maximum number of images to delete in a single automated image cleanup cycle. If set to less than 1, the value is ignored. | 5 | 5 |
 | `ECS_IMAGE_PULL_BEHAVIOR` | <default | always | once | prefer-cached > | The behavior used to customize the container image and digest pull process. If `default` is specified, the image/digest will be pulled remotely, if the pull fails then the cached image/digest on the instance will be used. If `always` is specified, the image/digest will be pulled remotely, if the pull fails then the task will fail. If `once` is specified, the image/digest will be pulled remotely if it has not been pulled before or if the image was removed by image cleanup, otherwise the cached image/digest on the instance will be used. If `prefer-cached` is specified, the image/digest will be pulled remotely if there is no cached image, otherwise the cached image/digest in the instance will be used. | default | default |
 | `ECS_IMAGE_PULL_INACTIVITY_TIMEOUT` | 1m | The time to wait after docker pulls complete waiting for extraction of a container. Useful for tuning large Windows containers. | 1m | 3m |