fixes 11961: dropdown alignment docs improvements
fixes 11961: dropdown alignment docs improvements

BS3 commits: b505c8557d4145b38257fc51d6ca4e7d98a0b62c

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