.bg-inverse's text color and background-color are the same, making text unreadable

Created by: jeradrutnam

I have fix this. It's available in the PR: https://github.com/twbs/bootstrap/pull/20130.

Please review the fix, https://github.com/jeradrutnam/bootstrap/commit/f5f98ec2452a63485236ef7ef0cada790b62be25