Resolves #10923

Rebased from #10930
Fixes issue #11122 -- navbar-fixed-bottom border

Enable border-top in .navbar-fixed-bottom
Update translation URL
Merge pull request #11141 from vincentchan/master

Update translation sites URL
fix #11144
FIx invalid element selector

`kbd` (keyboard) is right, not `kdb`. :P
Merge pull request #11150 from ZDroid/patch-1

FIx invalid element selector
add explicit copyright header to docs CSS & JS files; fixes #11112
even shorter banner; remove space between slash and period
Merge branch 'fix-11112'
copy change, add to buttons anchor section
Merge branch 'master' into navbar-button-docs
Merge pull request #11096 from twbs/navbar-button-docs

Resolves #10923
Warn about IE8 + Respond.js + file:// problem in examples; fix #11019
JS docs: add cross-reference to Getting Started mobile modal section
Merge pull request #11156 from twbs/mobile-modals-xref

JS docs: add cross-reference to Getting Started mobile modal section
Merge pull request #11155 from twbs/ie8-file-proto-respond.js-examples-warnings

Warn about IE8 + Respond.js + file:// problem in examples
(Not HTML) tag way is much better
Merge pull request #11166 from ZDroid/tag_way

(Not HTML) tag way is much better
Continue tag way implementation