Invoiceapidoc patch

Added the fallback address to the API documentation of the invoice command

lightningd/invoice.c

@@ -267,7 +267,8 @@ static void json_invoice(struct command *cmd,
 static const struct json_command invoice_command = {
     "invoice", json_invoice, "Create an invoice for {msatoshi} with {label} "
 			     "and {description} with optional {expiry} seconds "
-			     "(default 1 hour) and optional {preimage} "
+			     "(default 1 hour), optional {fallbacks} address list"
+                             "(default empty list) and optional {preimage} "
 			     "(default autogenerated)"};
 AUTODATA(json_command, &invoice_command);