#1617 Put social media in the footer

This is a follow-up on a larger discussion about our social media modules, accounts and the contact page in #1396 Since all other issues have been worked on I now start a separate discussion about putting our two most prominent social media accounts in the footer: mastodon and twitter. Why only these two? These are the two most active and prominent channels outside our homepage with 24.000 followers together. We use them basically daily and number of followers grow steadily. Other accounts could be added in the future but for now I think we also miss a good pr strategy of other accounts like peertube and youtube etc. A quick search has shown it is also very common to put social media buttons in the footer. I would do it as simple as this: