[Tails-dev] [review'n'merge] update links

Hello, in this branch I restore and update links I removed previously,
based on the redirections in .htaccess file.
I also update few other links.

Please review and merge.

Repo: https://git-tails.immerda.ch/xin/tails/
Branch: update_links
Last Commit: cdcc0adbde2b9f2c36e5da0418b30199bdaeaa61

Cheers.
xin