Updates the docs to reflect the intended change of not requiring a wrapping element. Instead of surrounding .tables with .table-responsive, just add it as a modifier. The associated CSS has also been updated and tweaked slightly.
Probably helpful to note that .table-bordered.table-responsive has had it's outer border removed. Since the <table> is now display: block, those borders will render double on horizontal scroll. This removes the border on the table, but keeps it on the elements. At times you'll see cut off table cells, but that's intentional and helps indicate scroll behavior.
Closes #18612 (closed) (though there was no bug fixed here).