This folder contains the index.<locale_name>.html file that contains a description of a given web application. This description will be displayed to the user in a separate help window after the user clicks on the "?" sign against the application listed in AV Repository (select Application Vault on the Server Administration page of Plesk to display the contents of AV Repository).
When creating the description file, one should follow the naming convention defined for such files. It requires that the file name specifies the locale settings, namely, the language and the dialect in which the document is written, in place of <locale_name>, e.g.:
index.en-US.html
index.en-UK.html
index.de-DE.html