Fix broken links in docs index file
Fix broken links in docs index file

Closes https://github.com/python-diamond/Diamond/issues/591

tusharmakkar08/Diamond,gg7/diamond,skbkontur/Diamond,tusharmakkar08/Diamond,gg7/diamond,tusharmakkar08/Diamond,MichaelDoyle/Diamond,tusharmakkar08/Diamond,skbkontur/Diamond,skbkontur/Diamond,MichaelDoyle/Diamond,skbkontur/Diamond,python-diamond/Diamond,python-diamond/Diamond,python-diamond/Diamond,gg7/diamond,MichaelDoyle/Diamond,gg7/diamond,MichaelDoyle/Diamond