[css] remove incorrect "visibility: hidden" answer from visually hide content question (#242)

Co-authored-by: Martin Duran <mduran@nerdery.com>

Author: martinjunior

questions/css-questions.md

@@ -195,7 +195,6 @@ CSS sprites combine multiple images into one single larger image. It is a common
 
 These techniques are related to accessibility (a11y).
 
-- `visibility: hidden`. However, the element is still in the flow of the page, and still takes up space.
 - `width: 0; height: 0`. Make the element not take up any space on the screen at all, resulting in not showing it.
 - `position: absolute; left: -99999px`. Position it outside of the screen.
 - `text-indent: -9999px`. This only works on text within the `block` elements.