Add fundrawtransactions new reserveChangeKey option to the release notes

Author: jonasschnelli

doc/release-notes.md

@@ -128,6 +128,16 @@ Call "getmininginfo" loses the "testnet" field in favor of the more generic "cha
 
 ### Wallet
 
+0.14.0 Fundrawtransaction change address reuse
+==============================================
+
+Before 0.14, `fundrawtransaction` was by default wallet stateless. In almost all cases `fundrawtransaction` does add a change-output to the outputs of the funded transaction. Before 0.14, the used keypool key was never marked as change-address key and directly returned to the keypool (leading to address reuse).
+Before 0.14, calling `getnewaddress` directly after `fundrawtransaction` did generate the same address as the change-output address.
+
+Since 0.14, fundrawtransaction does reserve the change-output-key from the keypool by default (optional by setting  `reserveChangeKey`, default = `true`)
+
+Users should also consider using `getrawchangeaddress()` in conjunction with `fundrawtransaction`'s `changeAddress` option.
+
 ### GUI
 
 ### Tests