signer/core: show helptext when clef rejects signing (#27538)

Co-authored-by: Martin Holst Swende <martin@swende.se>

signer/core/api.go

@@ -553,6 +553,7 @@ func (api *SignerAPI) SignTransaction(ctx context.Context, args apitypes.SendTxA
 	// If we are in 'rejectMode', then reject rather than show the user warnings
 	if api.rejectMode {
 		if err := msgs.GetWarnings(); err != nil {
+			log.Info("Signing aborted due to warnings. In order to continue despite warnings, please use the flag '--advanced'.")
 			return nil, err
 		}
 	}
@@ -625,6 +626,7 @@ func (api *SignerAPI) SignGnosisSafeTx(ctx context.Context, signerAddress common
 	// If we are in 'rejectMode', then reject rather than show the user warnings
 	if api.rejectMode {
 		if err := msgs.GetWarnings(); err != nil {
+			log.Info("Signing aborted due to warnings. In order to continue despite warnings, please use the flag '--advanced'.")
 			return nil, err
 		}
 	}