[Docs] Remove redundant visually hidden "(current)" from pagination controls

https://getbootstrap.com/docs/4.5/components/pagination/ https://v5.getbootstrap.com/docs/5.0/components/pagination/

Remove the <span class="visually-hidden">(current)</span> where the controls already have aria-current

xref https://github.com/twbs/bootstrap/pull/30079#issuecomment-708260201