[doc] Added metadata_column parameter usage example in mysql cdc acti…

…on (apache#2480)

docs/layouts/shortcodes/generated/mysql_sync_database.html

@@ -63,7 +63,7 @@
     </tr>
     <tr>
         <td><h5>--metadata_column</h5></td>
-        <td>--metadata_column is used to specify which metadata columns to include in the output schema of the connector. Metadata columns provide additional information related to the source data, such as the `table_name`, `database_name`, and `op_ts`. Each configuration should be specified in the format "key=value". See its <a href="https://ververica.github.io/flink-cdc-connectors/master/content/connectors/mysql-cdc.html#available-metadata">document</a> for a complete list of available metadata.</td>
+        <td>--metadata_column is used to specify which metadata columns to include in the output schema of the connector. Metadata columns provide additional information related to the source data, for example: --metadata_column table_name,database_name,op_ts. See its <a href="https://ververica.github.io/flink-cdc-connectors/master/content/connectors/mysql-cdc.html#available-metadata">document</a> for a complete list of available metadata.</td>
     </tr>
     <tr>
         <td><h5>--type_mapping</h5></td>

docs/layouts/shortcodes/generated/mysql_sync_table.html

@@ -67,7 +67,7 @@
     </tr>
     <tr>
         <td><h5>--metadata_column</h5></td>
-        <td>--metadata_column is used to specify which metadata columns to include in the output schema of the connector. Metadata columns provide additional information related to the source data, such as the `table_name`, `database_name`, and `op_ts`. Each configuration should be specified in the format "key=value". See its <a href="https://ververica.github.io/flink-cdc-connectors/master/content/connectors/mysql-cdc.html#available-metadata">document</a> for a complete list of available metadata.</td>
+        <td>--metadata_column is used to specify which metadata columns to include in the output schema of the connector. Metadata columns provide additional information related to the source data, for example: --metadata_column table_name --metadata_column database_name --metadata_column op_ts. See its <a href="https://ververica.github.io/flink-cdc-connectors/master/content/connectors/mysql-cdc.html#available-metadata">document</a> for a complete list of available metadata.</td>
     </tr>
     <tr>
         <td><h5>--mysql_conf</h5></td>