Link to the core po files which need to be translated
Originally created by @Anonymous on #9118 (Redmine)
On the translation documentation, describe and link to the core po files
out of which 25% need to be translated so that a language is considered
as an available choice for the website tails.boum.org
The link should go to this file:
https://tails.boum.org/contribute/l10n_tricks/core_po_files.txt
Feature Branch: bitingbird:doc/9118-translate_core