Added link to renderer tests issue to README.
Added link to renderer tests issue to README.

Dador/libjass,Dador/libjass,joshuabrown-ellation/libjass,Dador/libjass,joshuabrown-ellation/libjass,joshuabrown-ellation/libjass,Arnavion/libjass,Arnavion/libjass,Arnavion/libjass