feat(iam): add unknown

Author: ldecarvalho-doc

identity-and-access-management/iam/how-to/view-logs.mdx

@@ -25,6 +25,7 @@ dates:
     Some of the principals who performed the actions might appear as `Unknown` in the logs. This could be due to a couple of reasons: <br />
     - The principal used to be a part of the Organization, but since performing the action is no longer a part of it. For example, if a user or an application is removed from an Organization, their name will no longer appear in the list, but the user or application ID still indicates it was them who performed the action.
     - You do not have the IAM permissions necessary to see the details of a principal.
+    - A user was deleted after the invitation to join an Organization was rejected or expired.
     <br />
 
     Besides `unknown`, you might also see principals named `Scaleway`. This happens when an action is performed by Scaleway. For example, whenever a new Organization is created 3 groups are created by default. This action is technically performed by Scaleway, and will be described as such in the logs.<br /><br />