docs(srv): add notes on secret regionalization and jobs MTA-5912 (#4824)

Author: SamyOubouaziz

pages/serverless-jobs/faq.mdx

@@ -145,6 +145,10 @@ skopeo copy --override-os linux docker://docker.io/alpine:latest docker://rg.fr-
 
 Yes, you can use sensitive data such as API secret keys, passwords, TLS/SSL certificates, or tokens. Serverless Jobs seamlessly integrates with [Secret Manager](/secret-manager/), which allows you to securely reference sensitive information within your jobs. Refer to the [dedicated documentation](/serverless-jobs/how-to/reference-secret-in-job/) for more information.
 
+<Message type="note">
+Serverless Jobs can only reference secrets stored in the same [region](/secret-manager/concepts/#region).
+</Message>
+
 ## Network and storage
 
 ### How can I configure access to a Private Network or Virtual Private Cloud (VPC)?

pages/serverless-jobs/how-to/reference-secret-in-job.mdx

@@ -20,6 +20,10 @@ You can reference any secret stored in Secret Manager in a job, without having t
 
 A [job run](/serverless-jobs/concepts/#job-run) accesses each secret at startup, and each access generates a call to the Secret Manager API, which is billed accordingly. Refer to the [Secret Manager pricing](/secret-manager) for more information.
 
+<Message type="important">
+Serverless Jobs can only reference secrets stored in the same [region](/secret-manager/concepts/#region).
+</Message>
+
 <Macro id="requirements" />
 
 - A Scaleway account logged into the [console](https://console.scaleway.com)
@@ -37,6 +41,11 @@ A [job run](/serverless-jobs/concepts/#job-run) accesses each secret at startup,
 
 4. Select the secret you want to reference, and the desired version, then click **Select reference method**.
 
+    <Message type="note">
+    If the secret you want to reference does not appear in the list, make sure it is stored in the same [region](/
+    secret-manager/concepts/#region) as your Serverless Job. 
+    </Message>
+
 5. Select the desired reference method:
 
   - **File**: copies the encrypted value of your secret to a file stored at the indicated location within your job. This method is recommended for large or complex data. For example, if your secret is a certificate, you can store it as a file in the `/my-certificates` folder in your job.