Update html5lib link version in README.rstl
Update html5lib link version in README.rstl

Link to html5lib pointed to previously removed google code page. Also, version in requirements did not match the README.
tinjyuu/xhtml2pdf,bogdal/xhtml2pdf,jensadne/xhtml2pdf,chrisglass/xhtml2pdf,xhtml2pdf/xhtml2pdf,chrisglass/xhtml2pdf,xhtml2pdf/xhtml2pdf,orbitvu/xhtml2pdf,jensadne/xhtml2pdf,orbitvu/xhtml2pdf,trib3/xhtml2pdf,b-me/xhtml2pdf,trib3/xhtml2pdf,tinjyuu/xhtml2pdf,bogdal/xhtml2pdf,b-me/xhtml2pdf