Fix missing `rst2html5-reveal.css` css file in MANIFEST.in
Fix missing `rst2html5-reveal.css` css file in MANIFEST.in

marianoguerra/rst2html5,keith-gray-powereng/rst2html5,wdv4758h/rst2html5tools,emi80/rst2html5,keith-gray-powereng/rst2html5,marianoguerra/rst2html5,marianoguerra/rst2html5,wdv4758h/rst2html5tools,emi80/rst2html5