As per discussion on https://github.com/w3c/wai-wcag-quickref/issues/2
and #13554

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Also, use id rather class name for the navigation, as it's unique and
lets us use correct aria-controls (and without the use of id,
aria-expanded does not get updated correctly by the current dropdown
toggle script)

Before, most callouts hierarchically came under Examples > Four
directions, which is not appropriate. Now they're under Markup

Include callout explicitly mentioning tooltips should only be added to
focusable elements. Closes #16134

Closes #16113
Closes #16114

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Refs #15947

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Closes #15948 by merging it.

Closes #15946 by merging it.

Closes #15915 by merging it.

Fix URL to match the keyword

X-Ref #15742

cc: @mdo

[Fixes #15928] Encourage use of icons with form validation states for colorblind users

Update text per @patrickhlauke's feedback

Update text per @patrickhlauke's feedback.

Fix stupid grammar mistake

Fixes #15106.
Closes #15910.

Added attributes rel and target.

Fixes #15882 — Use an ID as the example for Scrollspy so that it is more clear that this is for use with a single nav.

Update Creative Commons link to HTTPS.

Normalized the heading hierarchy in the documentation for the Button groups component.

Normalized the heading hierarchy in the documentation for the Dropdowns component.

Related to #15823, I would be interested in officially recommending a keyword such as `twbs-bootstrap` so that we can more easily showcase plugins and extensions for Bootstrap without requiring additional curation by the admins / collabs of TWBS

specificity

Add additional comment to docs

Fix capitalization

Update tag per @mdo's recommendation