docs(ddx): add warning about email validation

Author: bene2k1

pages/dedibox-account/how-to/update-email.mdx

@@ -15,6 +15,11 @@ categories:
 
 Every Scaleway Dedibox account is associated with a specific email address. In the event that your email address undergoes any changes, you have the option to update this information directly within your account settings.
 
+<Message type="important">
+  To enhance the security of your Dedibox account and ensure a smooth experience, it is required to verify your email address.
+  In case you have not yet verified the email address linked to your Dedibox account, please complete the steps below.
+</Message>
+
 <Macro id="requirements" />
 
 - A Dedibox account logged into the [console](https://console.online.net)