Add examples for adding extra TLVs to a spontaneous payment

snippets/go/go.mod

@@ -2,6 +2,6 @@ module main
 
 go 1.19
 
-require github.com/breez/breez-sdk-go v0.2.10
+require github.com/breez/breez-sdk-go v0.2.15
 
 replace github.com/breez/breez-sdk-go => ./packages/breez-sdk-go

snippets/go/send_spontaneous_payment.go

@@ -1,6 +1,7 @@
 package example
 
 import (
+	"encoding/hex"
 	"log"
 
 	"github.com/breez/breez-sdk-go/breez_sdk"
@@ -17,3 +18,22 @@ func SendSpontaneousPayment() {
 	}
 	// ANCHOR_END: send-spontaneous-payment
 }
+func SendSpontaneousPaymentWithTlvs() {
+	// ANCHOR: send-spontaneous-payment-with-tlvs
+	value, _ := hex.DecodeString("Hello world!")
+	extraTlvs := []breez_sdk.TlvEntry{
+		breez_sdk.TlvEntry{
+			FieldNumber: uint64(34349334),
+			Value:       value,
+		},
+	}
+	sendSpontaneousPaymentRequest := breez_sdk.SendSpontaneousPaymentRequest{
+		NodeId:     "...",
+		AmountMsat: uint64(3_000_000),
+		ExtraTlvs:  &extraTlvs,
+	}
+	if response, err := sdk.SendSpontaneousPayment(sendSpontaneousPaymentRequest); err == nil {
+		log.Printf("%#v", response)
+	}
+	// ANCHOR_END: send-spontaneous-payment-with-tlvs
+}