consolidate relatedTarget docs in dropdown event docs
Specify `img` alternative text.
Expand caveat for disabled fieldsets and links
Redundant role="form" on <form>s
Redundant role="navigation" on <nav>s

plus one example that still used the old <div role="navigation"> and a
fix-up of the callout as per
https://github.com/twbs/bootstrap/issues/15109
Move context-specific callout to general tag usage
Move button-tags section to start of button section
add unit tests for Carousel's 'wrap' option
honor wrap option in Carousel.getItemForDirection; fixes #15144
Add modal autofocus example
Merge pull request #15135 from hillai/patch-1

Add modal autofocus example
Merge pull request #15139 from patrickhlauke/docs-button-section-restructure

Docs button section restructure
rm redundant role="button" from <button>
Merge pull request #15129 from twbs/examples-img-alt

Specify `img` alternative text.
Merge pull request #15152 from twbs/fix-15144

honor wrap option in Carousel.getItemForDirection
[skip validator]
Merge pull request #15125 from patrickhlauke/docs-clean-up

Docs clean up - unnecessary role attributes, callout clarifications
Since Safari has released new fixed versions, we're unlikely to take any further action on this.
Fix name spelling
Merge pull request #15156 from Quy/master

Fix spelling of necolas' last name
Revert "Follow-up to #13074: use spec syntax instead of deprecated mixins"

This reverts commit b10b373c6019666dbe1152245c9efdf214ceaa6a.

Resolves #14937.