remove unneeded top table of contents in "extending frontend" doc
remove unneeded top table of contents in "extending frontend" doc

pombredanne/numba,gmarkall/numba,seibert/numba,gdementen/numba,stefanseefeld/numba,numba/numba,cpcloud/numba,stuartarchibald/numba,pombredanne/numba,pitrou/numba,sklam/numba,stefanseefeld/numba,IntelLabs/numba,IntelLabs/numba,stefanseefeld/numba,GaZ3ll3/numba,numba/numba,stefanseefeld/numba,gmarkall/numba,jriehl/numba,ssarangi/numba,sklam/numba,cpcloud/numba,seibert/numba,ssarangi/numba,stuartarchibald/numba,stonebig/numba,numba/numba,ssarangi/numba,stefanseefeld/numba,stuartarchibald/numba,pombredanne/numba,seibert/numba,stonebig/numba,pitrou/numba,stonebig/numba,stonebig/numba,ssarangi/numba,jriehl/numba,pitrou/numba,gdementen/numba,stuartarchibald/numba,gdementen/numba,IntelLabs/numba,GaZ3ll3/numba,ssarangi/numba,cpcloud/numba,seibert/numba,IntelLabs/numba,numba/numba,gdementen/numba,gdementen/numba,numba/numba,sklam/numba,sklam/numba,GaZ3ll3/numba,gmarkall/numba,IntelLabs/numba,cpcloud/numba,gmarkall/numba,cpcloud/numba,pombredanne/numba,jriehl/numba,sklam/numba,gmarkall/numba,pombredanne/numba,jriehl/numba,seibert/numba,GaZ3ll3/numba,stonebig/numba,GaZ3ll3/numba,pitrou/numba,stuartarchibald/numba,pitrou/numba,jriehl/numba