Clarify migration docs to remove mention of .table-responsive being for the parent element vs the table element itself (#25539)

Author: mdo

docs/4.0/migration.md

@@ -144,7 +144,6 @@ New to Bootstrap 4 is the [Reboot]({{ site.baseurl }}/docs/{{ site.docs_version
 ### Tables
 
 - Nearly all instances of the `>` selector have been removed, meaning nested tables will now automatically inherit styles from their parents. This greatly simplifies our selectors and potential customizations.
-- Responsive tables no longer require a wrapping element. Instead, just put the `.table-responsive` right on the `<table>`.
 - Renamed `.table-condensed` to `.table-sm` for consistency.
 - Added a new `.table-inverse` option.
 - Added table header modifiers: `.thead-default` and `.thead-inverse`.