Remove incorrect action from the IAM policy (#531)

Co-authored-by: bryan-aguilar <[email protected]>

Author: DewaldDeJager

src/docs/getting-started/container-insights/ecs-prometheus.mdx

@@ -307,8 +307,7 @@ Policy document merged from <Link to="/docs/setup/ecs/create-iam-policy">ECS set
                 "ecs:DescribeContainerInstances",
                 "ecs:DescribeServices",
                 "ecs:DescribeTasks",
-                "ecs:DescribeTaskDefinition",
-                "ecs:DescribeInstances"
+                "ecs:DescribeTaskDefinition"
             ],
             "Resource": "*"
         }