Merge bitcoin/bitcoin#22979: doc: Fix walletdisplayaddress RPC doc

fa22ddc7d5 doc: Fix walletdisplayaddress RPC doc (MarcoFalke)

Pull request description:

  Previously the description was empty

ACKs for top commit:
  fanquake:
    ACK fa22ddc7d5

Tree-SHA512: f8898f9545378dd9f68eba036745776c1bc8d43c4753a19fcd9c3d945a11d9e07cd394d9ed215c2d090964830f785f812f18608f04fc7e2fb73730fc77c5d807

src/wallet/rpcwallet.cpp

@@ -4650,10 +4650,11 @@ static RPCHelpMan upgradewallet()
 #ifdef ENABLE_EXTERNAL_SIGNER
 static RPCHelpMan walletdisplayaddress()
 {
-    return RPCHelpMan{"walletdisplayaddress",
+    return RPCHelpMan{
+        "walletdisplayaddress",
         "Display address on an external signer for verification.",
         {
-            {"address",     RPCArg::Type::STR, RPCArg::Optional::NO, /* default_val */ "", "bitcoin address to display"},
+            {"address", RPCArg::Type::STR, RPCArg::Optional::NO, "bitcoin address to display"},
         },
         RPCResult{
             RPCResult::Type::OBJ,"","",