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

The Known Issues page of the documentation mentioned a problem with
IPython versions prior to 0.13.2, while currently the minimum version
supported by Astropy is 4.2 (see issue #11005).

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