[skip sauce]

Saves 3.4KB.

Move all callouts to be adjacent to each other
Combine JS-related callouts into a single callout

adding explicit aria-expanded="false" initial state (so they're
correctly announced by AT as being collapsed), and - in the case of
old-school use of <a> - role="button"

Closes #14951 by merging it.

- add aria-hidden="true" to avoid SRs unintentionally reading out the
Unicode character (see
http://www.filamentgroup.com/lab/bulletproof_icon_fonts.html)
- callout with advice on accessible icon usage
- replaced sr-only text in examples with (in the case of button) cleaner
aria-label
- additional example of icon used to convey meaning (in a
non-interactive control)

Refs https://github.com/twbs/bootlint/pull/153
[skip sauce]

[skip sauce]

Refs #14409

Refs #14409

Signed-off-by: Geoff Pleiss <gpleiss@pivotal.io>

Signed-off-by: Jenn Dodd <jedodd@pivotal.io>

[ci skip]

Refs #14598
[skip sauce]

* move unrelated .btn-primary example out of the pills subsection
* remove excessive .nav-stacked example

Refs #14362

Refs #13554.
Per https://github.com/paypal/bootstrap-accessibility-plugin/blob/master/README.md#tab-panel
Credit: https://github.com/paypal/bootstrap-accessibility-plugin

[skip sauce]

Follow-up to e9374c06
Per https://github.com/paypal/bootstrap-accessibility-plugin/commit/f203dea4b6d17264d7b776f02feaeeaa386cc9b2
Credit: https://github.com/paypal/bootstrap-accessibility-plugin & @rohk

[skip sauce]