Docs: screen reader helper/visibility utility tweaks (!31133) · Merge requests · Bootstrap / bootstrap · GitLab

Merged Patrick H. Lauke requested to merge v5-docs-sr-visibility into main Jun 21, 2020

rename "Screen readers" helper to "Visually hidden" (in future, may consider actually renaming the classes as well? .visually-hidden / .visually-hidden-focusable or similar?)
reword description for visibility utility, emphasise/call out the fact that .invisible hides stuff from AT