improve landing page

[mfc]

• one needs to click on a language in order to get to the content but that is not communicated to the user
• quite difficult for a new user to navigate (lot of text that is probably not necessary, such as the second paragraph. the fourth paragraph could go into an about page)
  • actually most of the content is a repeat of the introduction section, so maybe the landing page is just:
    • language selection
    • very brief description

https://github.com/RaReNet/DFAK/blob/gh-pages/index.html