tb-manual: Update Security Levels
This commit incorporates following change to https://gitweb.torproject.org/tor-browser/user-manual.git
"Security Levels" information should be updated to replace "High, Medium, Low" levels with the current "Safest, Safer, Standard" information/configuration. https://lists.torproject.org/pipermail/www-team/2018-June/000432.html
C/media/security-slider/slider_window.png is changed. Note: To ensure that image and text are synchronized all languages and images need to be changed as well.
Repository: https://git.schokokeks.org/tor-tb-manual.git/?tor-tb-manual.git
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information