chore(readme): add awscli command to generate yaml file

Signed-off-by: nitrocode <[email protected]>

Author: nitrocode

README.md

@@ -35,6 +35,23 @@ findings:
       status: "SUPPRESED"
 ```
 
+The yaml file can be autogenerated from existing suppressions using this `awscli` command with `yq`.
+Feel free to remove `title` and `resource_id` keys. I use those as inline comments.
+Remember the `findings` parent key.
+
+```bash
+aws securityhub get-findings \
+  --filters '{"WorkflowStatus": [{"Value": "SUPPRESSED", "Comparison": "EQUALS"}] }' \
+  --query 'Findings.{
+    id: Id,
+    product_arn: ProductArn,
+    note: { text: Note.Text },
+    workflow: { status: `"SUPPRESSED"` }
+    title: Title,
+    resource_id: Resources[0].Id,
+  }' | yq -P . > findings.yaml
+```
+
 ---
 
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