[DOCS] SAML with Azure Active Directory using outdate API

This [page](https://www.elastic.co/guide/en/cloud/current/ec-securing-clusters-saml-azure.html) the last section for Configure SAML with Azure AD to access Kibana that discusses "Role Mapping" has an example that leverages an outdate API. Instead of `POST /_xpack/security/role_mapping/SAML_kibana`, the API should be `POST /_security/role_mapping/SAML_kibana`

This example could be made more complete by showing how to create a role against an Active Directory group rather than which I don't believe is a default returned from Azure AD into our Name field. By default, I believe its the user's principal, which based upon the example configurations above would be the users email address.