[doc] release note for relaxing requirement of all unconfirmed parents present

Author: glozow

doc/release-notes-31385.md

@@ -0,0 +1,14 @@
+RPC
+
+The `submitpackage` RPC, which allows submissions of child-with-parents
+packages, no longer requires that all unconfirmed parents be present. The
+package may contain other in-mempool ancestors as well. (#31385)
+
+P2P
+
+Opportunistic 1-parent-1-child package relay has been improved to handle
+situations when the child already has unconfirmed parent(s) in the mempool.
+This means that 1p1c packages can be accepted and propagate, even if they are
+connected to broader topologies: multi-parent-1-child (where only 1 parent
+requires fee-bumping), grandparent-parent-child (where only parent requires
+fee-bumping) etc. (#31385)