fix sphinx build warning
fix sphinx build warning

As warnings are treated as errors on public CI.

Warning, treated as error:
../CHANGE_LOG:75:Inline emphasis start-string without end-string.
Makefile:53: recipe for target 'html' failed
make: *** [html] Error 2

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