docs: clear up relative position confusion (#8102)
* docs: clear up relative position cofusion
* Update packages/@react-aria/visually-hidden/docs/VisuallyHidden.mdx
Co-authored-by: Yihui Liao <44729383+yihuiliao@users.noreply.github.com>
---------
Co-authored-by: Yihui Liao <44729383+yihuiliao@users.noreply.github.com>