twitter/bootstrap — pull request #7500 by JamieKnight (2013-04-07 14:26:02+00:00)
Title: Update docs to add warning about accessibility implications of using icons without any text

Spotted that one of the icons examples would be inaccessible to screen reader users so added a "heads up" to warn future users. I guess for many this won't matter, but for some this may save them a headache when tested.