Fix changelog section with correct syntax

At least accoding to the docs I can find here
https://docs.pagure.org/Fedora-Infra.rpmautospec/opting-in.html

Signed-off-by: Simo Sorce <simo@redhat.com>

cyrus-sasl.spec

@@ -388,4 +388,5 @@ getent passwd %{username} >/dev/null || useradd -r -g %{username} -d %{homedir}
 %{_mandir}/man3/*
 %{_sbindir}/sasl2-shared-mechlist
 
+%changelog
 %autochangelog