Document env-vars for refprune
Document env-vars for refprune

numba/numba,IntelLabs/numba,IntelLabs/numba,seibert/numba,numba/numba,gmarkall/numba,IntelLabs/numba,stuartarchibald/numba,seibert/numba,seibert/numba,gmarkall/numba,IntelLabs/numba,gmarkall/numba,stuartarchibald/numba,gmarkall/numba,cpcloud/numba,stuartarchibald/numba,cpcloud/numba,IntelLabs/numba,stonebig/numba,cpcloud/numba,seibert/numba,numba/numba,stonebig/numba,seibert/numba,stuartarchibald/numba,gmarkall/numba,stonebig/numba,stuartarchibald/numba,stonebig/numba,numba/numba,stonebig/numba,cpcloud/numba,cpcloud/numba,numba/numba