docs: add documentation for deprecation, new field and renamed input

Author: kwvg

doc/release-notes-6665.md

@@ -0,0 +1,13 @@
+Updated RPCs
+------------
+
+* The input field `ipAndPort` has been renamed to `coreP2PAddrs`.
+  * `coreP2PAddrs` can now, in addition to accepting a string, accept an array of strings, subject to validation rules.
+
+* The key `service` has been deprecated for some RPCs (`decoderawtransaction`, `decodepsbt`, `getblock`, `getrawtransaction`,
+  `gettransaction`, `masternode status` (only for the `dmnState` key), `protx diff`, `protx listdiff`) and has been replaced
+  with the field `addresses`.
+  * The deprecated field can be re-enabled using `-deprecatedrpc=service` but is liable to be removed in future versions
+    of Dash Core.
+  * This change does not affect `masternode status` (except for the `dmnState` key) as `service` does not represent a payload
+    value but the external address advertised by the active masternode.