DOC: Fix typo
DOC: Fix typo

[ci skip]

Co-authored-by: Derek Homeier <955e65eba8e58aa01aa289170b3c5b72f3c4064d@gwdg.de>
larrybradley/astropy,astropy/astropy,mhvk/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,dhomeier/astropy,lpsinger/astropy,StuartLittlefair/astropy,pllim/astropy,saimn/astropy,astropy/astropy,dhomeier/astropy,aleksandr-bakanov/astropy,pllim/astropy,larrybradley/astropy,mhvk/astropy,pllim/astropy,larrybradley/astropy,saimn/astropy,StuartLittlefair/astropy,lpsinger/astropy,dhomeier/astropy,saimn/astropy,larrybradley/astropy,saimn/astropy,astropy/astropy,mhvk/astropy,dhomeier/astropy,lpsinger/astropy,StuartLittlefair/astropy,astropy/astropy,saimn/astropy,mhvk/astropy,aleksandr-bakanov/astropy,astropy/astropy,larrybradley/astropy,mhvk/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,pllim/astropy,lpsinger/astropy,dhomeier/astropy,pllim/astropy