use pretty permalinks

[shushugah]

In order to ensure url's are unique for each event, we want to also use the /:year/:month/:day based on the file name, and enabling permalink pretty does all that by default, as well as the categories. See https://devhints.io/jekyll

and it also hides extentions, so no more /en/events.html now it's just /en/events

[ferbsx]

ooh I like this! Thank you for doing it 😍