add modal 'remote' option semantics change to migration docs; fixes 10585
add modal 'remote' option semantics change to migration docs; fixes 10585

BS3 commits: 306d850d3a710fd2124b05b8ff23b7f498f3eaae

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