chore: add missing change log for saml SSO Entra Id support

changes/ee/feat-11778.en.md

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+Support Azure Entra Id for saml single sign on.
+
+## Hight Light known issue:
+Signed SAML `AuthnRequest` is not fully supported yet by Azure Entra ID.
+See also for more details:
+[single-sign-on-saml-protocol#signature](https://learn.microsoft.com/en-us/azure/active-directory/develop/single-sign-on-saml-protocol#signature)