Release notes for RHEL-9 rp_filter setting

Related to: #2423
Signed-off-by: Sridhar Gaddam <sgaddam@redhat.com>

release-notes/20230426-rhel9-fix.md

@@ -0,0 +1,5 @@
+<!-- markdownlint-disable MD041 -->
+Submariner now ensures that reverse path filtering setting is properly applied
+on the `vx-submariner` and `vxlan-tunnel` interfaces after they are created.
+This fix was necessary for RHEL9 nodes where the setting was sometimes getting
+overwritten.