Write proper website description for search engines

Currently the website's description is set to the site's title (e.g. "Fachschaft Elektro- und Informationstechnik"). This should be changed to a seperate description parameter, configured in config/_default/config.toml.

Google has an extra page with more information on description meta tags.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information