remove fork-me (#457)

Removed the old "fork me" from the top right corner of the landing page. The image is no longer accessible and it also feels dated.

Author: orbeckst

index.md

@@ -62,12 +62,6 @@ If you find MDAnalysis useful and would like to support its continued developmen
     Donations are made through [our fiscal sponsor][], [NumFOCUS][], which is a 501(c)(3) non-profit charity in the United States; as such, donations to NumFOCUS are tax-deductible as allowed by law.  As with any donation, you should consult with your personal tax adviser or the IRS about your particular tax situation.
 </small>
 
-<a href="https://github.com/MDAnalysis/mdanalysis"><img style="position: absolute; top:
-0; right: 0; border: 0;"
-src="https://camo.githubusercontent.com/a6677b08c955af8400f44c6298f40e7d19cc5b2d/68747470733a2f2f73332e616d617a6f6e6177732e636f6d2f6769746875622f726962626f6e732f666f726b6d655f72696768745f677261795f3664366436642e706e67"
-alt="Fork me on GitHub"
-data-canonical-src="https://s3.amazonaws.com/github/ribbons/forkme_right_gray_6d6d6d.png"></a>
-
 [NumFOCUS]: https://www.numfocus.org
 [our fiscal sponsor]: {{site.baseurl}}/about#partners
 [NumPy]: https://numpy.org/