Remove an obsolete known issue [ci skip]
Remove an obsolete known issue [ci skip]

The Known Issues page of the documentation mentions a problem with NumPy
versions 1.10.0 to 1.10.5, but the minimum NumPy version required by
Astropy LTS is already 1.16.0.

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