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);
Add Welcome section to docs

* Fixes unrelated typo in readme
* Add new Welcome section with history, team, callouts, and community
subsections
* Redesigns callouts to be a bit lighterweight with colored headings
shorter avatar urls
use irc link
Merge branch 'master' into docs_welcome
adding required attribute for example signin form
Copy edits from @cvrebert and @juthilo
dat @juthilo edit
dat hash
move to separate about page
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
Change clone protocol from git:// to https://

Cloning with git: protocol doesn't allow to change anything in `.git/`, like when using `git pull`.
Change border to border-radius

Border isn't set, but border-radius is.
Jumbotron: remove the hard-coded font-size from jumbotron.less and moved it into variables.less where other .font-size-xxxxx things now live.
merge in new ads
Insert comma to fix validation warning

BS doesn't support IE6/IE7, so comma can be inserted.
Sort tasks alphabetically
The Jumbotron font-size LESS variable now conforms to the '@{bootstrapClass}-font-size' naming scheme.
The customizer now displays and collects the new Jumbotron font-size LESS variable
Good catch by @juthilo - omitted the modified  in a prior commit.