Update about.html

Updated link to article.

mutalyzer/website/templates/about.html

@@ -98,13 +98,11 @@ Dunnen.
 </p>
 
 <p>
-Since references to WWW-sites are not yet acknowledged as citations,
-please mention
-<a href="http://www.ncbi.nlm.nih.gov/pubmed/18000842">
-  &quot;Wildeman M et al. (2008). Improving sequence variant
-  descriptions in mutation databases and literature using the
-  Mutalyzer sequence variation nomenclature checker. Hum Mutat 29,
-  6-13&quot;</a> (<a href="http://dx.doi.org/10.1002/humu.20654">direct
+Please mention
+<a href="https://pubmed.ncbi.nlm.nih.gov/33538839/">
+  &quot;Lefter M et al. (2021). Mutalyzer 2: Next Generation HGVS
+  Nomenclature Checker. Bioinformatics, btab051&quot;</a> 
+(<a href="https://doi.org/10.1093/bioinformatics/btab051">direct
   link</a>) when referring to these pages.
 </p>