fixes 9522

BS3 commit f058a6a3ea6196af859303ff4611fd9807842f7d
fix copypasta-o to fully fix 9295

BS3 commit 3a67054536338c613c43078b6f48e5f502bf527d
add callout about browser zooming to browser support section

BS3 commit 083b7c0981656ff1c660482653645bb9e4f71543
more accurate grid table breakpoint numbers. add grid docs about responsive column clearing. fix inaccurate comment in media query docs. fixes 9522

BS3 commits 70b0fb445ee373811ea952a0936493c4f574fba2,
6e26f846cdb96060afb0530f1d34fdfc2a11f83d,
c84d34b5f1ae6908c5a0b524c17b81103b831f35,
f058a6a3ea6196af859303ff4611fd9807842f7d