Thank you for the information. I didn’t know the language packs feature.
But when I put the language files in the wp-content/languages/plugins/varnish-http-purge
, it didn’t work.
Here is the solution:
* Add load_plugin_textdomain( 'varnish-http-purge' );
to the plugin file
* Put the translation files into wp-content/languages/plugins/
, no need to create nested directory.