auth docs: add note about EL9 and SHA1

diff --git a/docs/upgrading.rst b/docs/upgrading.rst
index f1fed5ace31e60e25c1912a6fd0964fa05c473f1..d728aeecc46044d387869ed06442af9fe6b27784 100644 (file)
--- a/docs/upgrading.rst
+++ b/docs/upgrading.rst
@@ -50,6 +50,11 @@ Various custom queries have been renamed.
 any version to 4.8.x
 --------------------
 
+Use of (RSA-)SHA1 on Red Hat Enterprise Linux 9 and derivatives
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If you are using PowerDNS Authoritative Server on EL9, please read `this ticket about Red Hat's SHA1 deprecation and how it affects PowerDNS software <https://github.com/PowerDNS/pdns/issues/12890>`__.
+
 LMDB backend
 ^^^^^^^^^^^^