doc: Add 19501 release notes

Author: MarcoFalke

doc/release-notes.md

@@ -190,6 +190,9 @@ Wallet
   introduced unbroadcast set. See the "P2P and network changes" section for
   more information on the unbroadcast set. (#18038)
 
+- The `sendtoaddress` and `sendmany` RPCs accept an optional `verbose=True`
+  argument to also return the fee reason about the sent tx. (#19501)
+
 - The wallet can create a transaction without change even when the keypool is
   empty. Previously it failed. (#17219)