Added quick access link to the public SKIRT github on homepage
Added quick access link to the public SKIRT github on homepage

raesjo/SKIRT,raesjo/SKIRTcorona,SKIRT/SKIRT,raesjo/SKIRTcorona,raesjo/SKIRT,raesjo/SKIRT,SKIRT/SKIRT,raesjo/SKIRTcorona,SKIRT/SKIRT