doc: Merge release notes

Author: MarcoFalke

doc/release-notes-19988.md

@@ -82,6 +82,14 @@ P2P and network changes
   node using P2P relay. This version reduces the initial broadcast guarantees
   for wallet transactions submitted via P2P to a node running the wallet. (#18038)
 
+- The size of the set of transactions that peers have announced and we consider
+  for requests has been reduced from 100000 to 5000 (per peer), and further
+  announcements will be ignored when that limit is reached. If you need to dump
+  (very) large batches of transactions, exceptions can be made for trusted
+  peers using the "relay" network permission. For localhost for example it can
+  be enabled using the command line option `[email protected]`.
+  (#19988)
+
 - The Tor onion service that is automatically created by setting the
   `-listenonion` configuration parameter will now be created as a Tor v3 service
   instead of Tor v2. The private key that was used for Tor v2 (if any) will be