admin: remove named references to web analytics services Étienne Gilli mentioned via a Weblate comment that Piwik is now Matomo ( https://matomo.org/blog/2018/01/piwik-is-now-matomo/ ), and suggested changing the string in the code base. But in fact, there is no real reason to mention any one service. In fact, since the Kallithea project does not endorse any service, it is better to not list anything.