docs(iam): add link to the available permission sets (#2254)

Author: quantumsheep

docs/resources/iam_policy.md

@@ -7,6 +7,8 @@ page_title: "Scaleway: scaleway_iam_policy"
 
 Creates and manages Scaleway IAM Policies. For more information, see [the documentation](https://developers.scaleway.com/en/products/iam/api/v1alpha1/#policies-54b8a7).
 
+~> You can find a detailed list of all permission sets available at Scaleway in the permission sets [reference page](https://www.scaleway.com/en/docs/identity-and-access-management/iam/reference-content/permission-sets/).
+
 ## Example Usage
 
 ### Create a policy for an organization's project