pipeline: outputs: cloudwatch: Add missing log_group_class

Feature was introduced over a year ago in
fluent/fluent-bit#8832 but never documented.

Author: alexjfisher

pipeline/outputs/cloudwatch.md

@@ -26,6 +26,7 @@ See [here](https://github.com/fluent/fluent-bit-docs/tree/43c4fe134611da471e706b
 | log\_format           | An optional parameter that can be used to tell CloudWatch the format of the data. A value of json/emf enables CloudWatch to extract custom metrics embedded in a JSON payload. See the [Embedded Metric Format](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch\_Embedded\_Metric\_Format\_Specification.html).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
 | role\_arn             | ARN of an IAM role to assume (for cross account access).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
 | auto\_create\_group   | Automatically create the log group. Valid values are "true" or "false" (case insensitive). Defaults to false.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| log\_group\_class     | An optional parameter that can be used to specify the log storage class for new log groups, (created when `auto_create_group` is `true`). The storage class of pre-existing log groups can not be modified. Valid values are `STANDARD` (default) and `INFREQUENT_ACCESS`.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
 | log\_retention\_days  | If set to a number greater than zero, and newly create log group's retention policy is set to this many days. Valid values are: \[1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, 3653]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
 | endpoint              | Specify a custom endpoint for the CloudWatch Logs API.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
 | metric\_namespace     | An optional string representing the CloudWatch namespace for the metrics. See `Metrics Tutorial` section below for a full configuration.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |