refact(index.html): remove self closing slash for link tag.
refact(index.html): remove self closing slash for link tag.

You don't need it when doctype is HTML5 and also the others above already
don't have one.

Closes #232

dvn123/SINF,niharika88/Ztrackr,niharika88/Ztrackr,dvn123/SINF,dvn123/SINF