Add file type xlf to be searchable

I have followed the instructions found in https://community.adobe.com/t5/dreamweaver-discussions/add-file-type-to-be-searchable/m-p/10263339#M47336 https://community.adobe.com/t5/dreamweaver-discussions/add-file-type-to-be-searchable/m-p/10263339#M47336, but I can't find a way to search for text strings in unopened xlf files from the site. This kind of files are used for translations in Prestashop 1.7.