Fix favicons

[dankessler]

Favicons for the Computing Club currently link to twitter, github, and GScholar for George Cushen. We should either update where they point, or delete them if we don't have a relevant presence on that platform

[fontaine618]

I guess we could keep only the GitHub link (and update obviously)? What other pointers would be relevant?

[fontaine618]

It is fixed now, but I'll leave the issue open to eventually propose new links!