doc: Add release note

Author: amitiuttarwar

doc/release-notes-27213.md

@@ -0,0 +1,8 @@
+P2P and network changes
+------
+
+- Nodes with multiple reachable networks will actively try to have at least one
+  outbound connection to each network. This improves individual resistance to
+  eclipse attacks and network level resistance to partition attacks. Users no
+  longer need to perform active measures to ensure being connected to multiple
+  enabled networks.