Fix doctest for millianstrom
Fix doctest for millianstrom

saimn/astropy,saimn/astropy,pllim/astropy,StuartLittlefair/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,mhvk/astropy,mhvk/astropy,astropy/astropy,StuartLittlefair/astropy,pllim/astropy,astropy/astropy,saimn/astropy,pllim/astropy,astropy/astropy,larrybradley/astropy,larrybradley/astropy,mhvk/astropy,larrybradley/astropy,StuartLittlefair/astropy,larrybradley/astropy,astropy/astropy,pllim/astropy,astropy/astropy,mhvk/astropy,saimn/astropy,larrybradley/astropy,lpsinger/astropy,saimn/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,mhvk/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,lpsinger/astropy,pllim/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,lpsinger/astropy