docs(plugin): Add Credential Rotation attribute and explanation

plugin/service/storage/README.md

@@ -13,6 +13,7 @@ boundary storage-buckets create \
   -worker-filter '"minio-access" in "/tags/type"' \
   -attr endpoint_url="https://my-minio-instance.dev/s3-api" \
   -attr region=REGION \
+  -attr disable_credential_rotation=true \
   -secret access_key_id='KEY' \
   -secret secret_access_key='SECRET'
 ```
@@ -24,6 +25,11 @@ The following `attributes` are valid on a MinIO storage bucket resource:
 - `endpoint_url` (string, required): Fully-qualified endpoint pointing to a
   MinIO S3 API.
 - `region` (string, optional): The region to configure the storage bucket for.
+- `disable_credential_rotation` (bool, optional): Controls whether the plugin
+  will rotate the incoming credentials and manage a new MinIO service account.
+  If this attribute is set to `false`, or not provided, the plugin will rotate
+  the incoming credentials, using them to create a new MinIO service account,
+  then delete the incoming credentials.
 
 ### Secrets