changed attr('data-target') to data('target');

this will extend js interface, to be possible to setup targets for tabs as 
    var content=$('<div class="tab-pane">',{text: 'content'});
    var tab=('<li>',{html: $('<a>',{text: 'Main options'})}).addClass('active').data({target: $main,toggle: 'tab'}).appendTo(tabs);
adding required attribute for example signin form
Dropdown in panel header does not inherit its colors

Fix for issue #10627
Removed the unnecessary override and the !important from .wrap

In the sticky footer example there were some weird stuff..
Same fix for the navbar example of sticky footer
Use bootstrap.less file order in Customizer

Appending stylesheets by iterating the `__less` Hash creates an order
that is not the same as 'bootstrap.less'.

Some stylesheets like 'component-animations.less' and 'modals.less' have
selectors with matching specificity, and so file order decides which
style wins. This causes issue #10030 by putting `.fade.in` after
`.modal-backdrop.in` and gives the backdrop a higher opacity than
intended.

This change uses the Less ordering in 'bootstrap.less' to generate the
final stylesheets in the Customizer to make sure customized file
ordering matches the distribution file order.

Fixes #10030
remove comma separating the color and the color-stop in -webkit-linear-gradient in the #gradient .vertical mixin.
Unhardcode .table-responsive bottom margin
fix .table-responsive media query; refs #11067
remove dupe content
Merge branch 'master' of github.com:twbs/bootstrap

Conflicts:
	getting-started.html
fix about page html validation and run grunt
Merge pull request #11086 from twbs/table-responsive-breakpoint

fix .table-responsive media query; refs #11067
Merge pull request #11084 from ZDroid/variable_way

Unhardcode .table-responsive bottom margin
unnest the list-group-item link variation for #11085 and #11088
Merge branch 'master' of github.com:twbs/bootstrap

Conflicts:
	dist/css/bootstrap.min.css
extended hover state of linked versions of .thumbnail
Merge pull request #11091 from yokomizor/extended_thumbnail_hover_state

Extended hover state of linked versions of .thumbnail
add IDs to frequently-referenced parts of the docs
Merge pull request #10779 from ssorallen/customizer-bootstrap-less-order

Use bootstrap.less file order in Customizer