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
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
nuke commented out docs css
Ditch `&`, as `+ ...` is enought
Merge pull request #11102 from ZDroid/less-fix

Ditch `&`, as `+ ...` is enought
Add Note About Changing to MIT
Merge pull request #11105 from twbs/license-note

Add notes about dual-licensing contributions before switching to MIT in v3.1
update jumbotron docs; fixes #11109
Merge branch 'master' of github.com:twbs/bootstrap
Include a note about text-based form control styling

fixes #8824.
Merge pull request #11110 from nikolawannabe/patch-1

Include a note about text-based form control styling
add dots to class name references for consistency