Improve MySqlBulkCopy documentation. For #1012

Author: bgrainger

docs/content/api/MySqlConnector/MySqlBulkCopyType.md

@@ -17,11 +17,23 @@ Example code:
 // https://dev.mysql.com/doc/refman/8.0/en/insert-select.html
 var dataTable = GetDataTableFromExternalSource();
 
+// open the connection
 using var connection = new MySqlConnection("...;AllowLoadLocalInfile=True");
 await connection.OpenAsync();
+
+// attach an event handler to retrieve warnings/errors
+IReadOnlyList<MySqlError> errors = Array.Empty<MySqlError>();
+void InfoMessageHandler(object sender, MySqlInfoMessageEventArgs args) => errors = args.Errors;
+connection.InfoMessage += InfoMessageHandler;
+
+// bulk copy the data
 var bulkCopy = new MySqlBulkCopy(connection);
 bulkCopy.DestinationTableName = "some_table_name";
 await bulkCopy.WriteToServerAsync(dataTable);
+
+// check for errors
+connection.InfoMessage -= InfoMessageHandler;
+if (errors.Count != 0) { /* handle errors */ }
 ```
 
 ```csharp

src/MySqlConnector/MySqlBulkCopy.cs

@@ -29,11 +29,23 @@ namespace MySqlConnector
 	/// // https://dev.mysql.com/doc/refman/8.0/en/insert-select.html
 	/// var dataTable = GetDataTableFromExternalSource();
 	///
+	/// // open the connection
 	/// using var connection = new MySqlConnection("...;AllowLoadLocalInfile=True");
 	/// await connection.OpenAsync();
+	///
+	/// // attach an event handler to retrieve warnings/errors
+	/// IReadOnlyList<MySqlError> errors = Array.Empty<MySqlError>();
+	/// void InfoMessageHandler(object sender, MySqlInfoMessageEventArgs args) => errors = args.Errors;
+	/// connection.InfoMessage += InfoMessageHandler;
+	///
+	/// // bulk copy the data
 	/// var bulkCopy = new MySqlBulkCopy(connection);
 	/// bulkCopy.DestinationTableName = "some_table_name";
 	/// await bulkCopy.WriteToServerAsync(dataTable);
+	///
+	/// // check for errors
+	/// connection.InfoMessage -= InfoMessageHandler;
+	/// if (errors.Count != 0) { /* handle errors */ }
 	/// </code>
 	/// </summary>
 	/// <remarks><para><strong>Note:</strong> This API is a unique feature of MySqlConnector; you must