Make the warning about JSON BigQuery column type more precise (#33121)

sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/BigQueryIO.java

@@ -3747,7 +3747,7 @@ private <DestinationT> WriteResult continueExpandTyped(
             if (rowWriterFactory.getOutputType() == OutputType.JsonTableRow) {
               LOG.warn(
                   "Found JSON type in TableSchema for 'FILE_LOADS' write method. \n"
-                      + "Make sure the TableRow value is a parsed JSON to ensure the read as a "
+                      + "Make sure the TableRow value is a Jackson JsonNode to ensure the read as a "
                       + "JSON type. Otherwise it will read as a raw (escaped) string.\n"
                       + "See https://cloud.google.com/bigquery/docs/loading-data-cloud-storage-json#limitations "
                       + "for limitations.");