Fixes 11420: Update migration guide on split of .visible-/.hidden-desktop into .visible-/.hidden-md and .visible-/.hidden-lg
Fixes 11420: Update migration guide on split of .visible-/.hidden-desktop into .visible-/.hidden-md and .visible-/.hidden-lg

BS3 commits: 9bbdb87150dc8a324ce641380042fadd84d6d34e

todc/todc-bootstrap,todc/todc-bootstrap,2947721120/googlebt4,mozillo/todc-bootstrap,todc/todc-bootstrap,up2vs/todc-bootstrap,aaroncnhk/todc-bootstrap,2947721120/todc-bootstrap,ztx1491/todc-bootstrap