chore: fix some typos in comment (#2258)

Signed-off-by: eveneast <qcqs@foxmail.com>

cw_tron/lib/tron_client.dart

@@ -428,7 +428,7 @@ class TronClient {
     if (!request.isSuccess) {
       log("Tron TRC20 error: ${request.error} \n ${request.respose}");
       throw Exception(
-        'An error occured while creating the transfer request. Please try again.',
+        'An error occurred while creating the transfer request. Please try again.',
       );
     }
 

cw_zano/lib/api/model/destination.dart

@@ -1,5 +1,5 @@
 class Destination {
-  final BigInt amount;     // transfered as string
+  final BigInt amount;     // transferred as string
   final String address;
   final String assetId;
 

lib/core/node_address_validator.dart

@@ -19,7 +19,7 @@ class NodePathValidator extends TextValidator {
 }
 
 // NodeAddressValidatorDecredBlankException allows decred to send a blank ip
-// address which effectively clears the current set persistant peer.
+// address which effectively clears the current set persistent peer.
 class NodeAddressValidatorDecredBlankException extends TextValidator {
   NodeAddressValidatorDecredBlankException()
       : super(