cgit is a web interface (cgi) for git repositories, written in C. The folder /var/cache/cgit, must be owned by your webserver user. A sample /etc/cgitrc (you must provide one) is in the docs folder, and so are some example configuration files for apache and lighttpd. luacrypto or lua-md5 are optional dependencies (for avatars support), but first you have to build this against lua. If you want to use the email-libravatar-korg.lua filter or the email-gravatar-sbo.lua one, have a look also to the suggested css additions (in the docs folder).