Visible on-hover of link-transition class, this PR also
adds a description to the social media icons indicating that
they will open in a new window.
This way, users will be able to see and hear (via a reader)
when a tab will open in a new window.
This approach is based on the one outlined here:
https://medium.com/@svinkle/why-let-someone-know-when-a-link-opens-a-new-window-8699d20ed3b1
