Change logo links on home page

[kbenoit]

Replace the current trio starting with "Simplicity & flexibility" with:

• Software

  • Text: "A collection of R packages for the quantitative analysis of textual data, built around quanteda.
  • Links to: the new page created in Make Projects a link to a projects page #7.

• Events

  • Text: "Workshops, conferences, and training events for quantitative text analysis."
  • Links to: The News categories Training, Events added as part of Devise categories for News #6

• Learning resources

  • Links to https://tutorials.quanteda.io/, but we might want to add (eventually) a landing page for tutorials to allow us to include more learning resources.

Find some applicable icons for each one.