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
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
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
Merge pull request #10519 from zba/master

changed attr('data-target') to data('target');
Merge pull request #10533 from topsitemakers/master

adding required attribute for example signin form
In docs, recommend only <div> (not <span>) for putting tooltips on disabled elements

Per issue comments, `display: inline` elements like <span> don't work for this.
Resolves #10049
Merge pull request #11094 from twbs/address-10049

Recommend only <div> (not <span>) for putting tooltips on disabled elements
fix #10952
run grunt