docs: add guidelines about emphasis to a11y content

[adamjohnson]

What I did

1. Add docs about emphasis (bold, italic, underline, all caps) to the Content page under accessibility

Testing Instructions

1. Grab the biggest dictionary nearby
2. Grab any resources related to writing for accessibility
3. Read through my deluge of English words on the DP Accessibility ➡️ Content page
4. Edit me into oblivion

Notes to Reviewers

• Is there a link to another site that specifies RH guidelines for using bold or italics only?
• What'd I miss?

Closes #1947

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: f7071c682f0a03f15fc660d60a175e71fd645ad0

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[netlify[bot]]

✅ Deploy Preview for red-hat-design-system ready!

Name	Link
🔨 Latest commit	f7071c682f0a03f15fc660d60a175e71fd645ad0
🔍 Latest deploy log	https://app.netlify.com/sites/red-hat-design-system/deploys/670d310e46876a0008ef173c
😎 Deploy Preview	https://deploy-preview-1950--red-hat-design-system.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[github-actions[bot]]

Size Change: 0 B

Total Size: 185 kB

ℹ️ View Unchanged

Filename	Size
./elements.js	473 B
./elements/rh-accordion/context.js	162 B
./elements/rh-accordion/rh-accordion-header.js	2.77 kB
./elements/rh-accordion/rh-accordion-panel.js	1.37 kB
./elements/rh-accordion/rh-accordion.js	3.21 kB
./elements/rh-alert/rh-alert.js	4.34 kB
./elements/rh-audio-player/rh-audio-player-about.js	1.85 kB
./elements/rh-audio-player/rh-audio-player-rate-stepper.js	1.85 kB
./elements/rh-audio-player/rh-audio-player-scrolling-text-overflow.js	1.53 kB
./elements/rh-audio-player/rh-audio-player-subscribe.js	1.43 kB
./elements/rh-audio-player/rh-audio-player.js	13.2 kB
./elements/rh-audio-player/rh-cue.js	2 kB
./elements/rh-audio-player/rh-transcript.js	2.75 kB
./elements/rh-avatar/random-pattern-controller.js	2.72 kB
./elements/rh-avatar/rh-avatar.js	2.9 kB
./elements/rh-back-to-top/rh-back-to-top.js	2.1 kB
./elements/rh-badge/rh-badge.js	1.55 kB
./elements/rh-blockquote/rh-blockquote.js	1.41 kB
./elements/rh-breadcrumb/rh-breadcrumb.js	1.5 kB
./elements/rh-button/rh-button.js	4.24 kB
./elements/rh-card/rh-card.js	3.64 kB
./elements/rh-code-block/prism.css.js	822 B
./elements/rh-code-block/prism.js	572 B
./elements/rh-code-block/rh-code-block.js	7.25 kB
./elements/rh-cta/rh-cta.js	3.89 kB
./elements/rh-dialog/rh-dialog.js	4.78 kB
./elements/rh-dialog/yt-api.js	617 B
./elements/rh-footer/rh-footer-block.js	766 B
./elements/rh-footer/rh-footer-copyright.js	362 B
./elements/rh-footer/rh-footer-links.js	1.17 kB
./elements/rh-footer/rh-footer-social-link.js	964 B
./elements/rh-footer/rh-footer-universal.js	4.05 kB
./elements/rh-footer/rh-footer.js	5.01 kB
./elements/rh-health-index/rh-health-index.js	2.35 kB
./elements/rh-icon/rh-icon.js	2.37 kB
./elements/rh-icon/ssr.js	181 B
./elements/rh-menu/rh-menu.js	1.29 kB
./elements/rh-navigation-secondary/rh-navigation-secondary-dropdown.js	2.47 kB
./elements/rh-navigation-secondary/rh-navigation-secondary-menu-section.js	1.35 kB
./elements/rh-navigation-secondary/rh-navigation-secondary-menu.js	1.75 kB
./elements/rh-navigation-secondary/rh-navigation-secondary-overlay.js	571 B
./elements/rh-navigation-secondary/rh-navigation-secondary.js	5.27 kB
./elements/rh-navigation-secondary/test/fixtures.js	769 B
./elements/rh-pagination/rh-pagination.js	5.46 kB
./elements/rh-site-status/rh-site-status.js	2.5 kB
./elements/rh-skip-link/rh-skip-link.js	1.24 kB
./elements/rh-spinner/rh-spinner.js	1.43 kB
./elements/rh-stat/rh-stat.js	2.2 kB
./elements/rh-subnav/rh-subnav.js	2.72 kB
./elements/rh-surface/rh-surface.js	1.11 kB
./elements/rh-surface/test/elements.js	423 B
./elements/rh-switch/rh-switch.js	2.93 kB
./elements/rh-table/rh-sort-button.js	1.49 kB
./elements/rh-table/rh-table.js	3.54 kB
./elements/rh-tabs/context.js	160 B
./elements/rh-tabs/rh-tab-panel.js	1.04 kB
./elements/rh-tabs/rh-tab.js	3.01 kB
./elements/rh-tabs/rh-tabs.js	3.77 kB
./elements/rh-tag/rh-tag.js	2.84 kB
./elements/rh-tile/rh-tile-group.js	1.81 kB
./elements/rh-tile/rh-tile.js	5.15 kB
./elements/rh-timestamp/rh-timestamp.js	983 B
./elements/rh-tooltip/rh-tooltip.js	2.24 kB
./elements/rh-video-embed/rh-video-embed.js	4.6 kB
./lib/context/color/consumer.js	1.23 kB
./lib/context/color/controller.js	947 B
./lib/context/color/provider.js	2.08 kB
./lib/context/event.js	593 B
./lib/context/headings/consumer.js	722 B
./lib/context/headings/controller.js	1.12 kB
./lib/context/headings/provider.js	1.24 kB
./lib/DirController.js	565 B
./lib/elements/rh-context-demo/rh-context-demo.js	1.28 kB
./lib/elements/rh-context-picker/rh-context-picker.js	2.24 kB
./lib/environment.js	4.09 kB
./lib/functions.js	175 B
./lib/I18nController.js	1.38 kB
./lib/ScreenSizeController.js	849 B
./lib/ssr-controller.js	251 B
./react/rh-accordion/rh-accordion-header.js	199 B
./react/rh-accordion/rh-accordion-panel.js	185 B
./react/rh-accordion/rh-accordion.js	215 B
./react/rh-alert/rh-alert.js	184 B
./react/rh-audio-player/rh-audio-player-about.js	191 B
./react/rh-audio-player/rh-audio-player-rate-stepper.js	213 B
./react/rh-audio-player/rh-audio-player-scrolling-text-overflow.js	214 B
./react/rh-audio-player/rh-audio-player-subscribe.js	196 B
./react/rh-audio-player/rh-audio-player.js	183 B
./react/rh-audio-player/rh-cue.js	195 B
./react/rh-audio-player/rh-transcript.js	207 B
./react/rh-avatar/rh-avatar.js	173 B
./react/rh-back-to-top/rh-back-to-top.js	183 B
./react/rh-badge/rh-badge.js	174 B
./react/rh-blockquote/rh-blockquote.js	179 B
./react/rh-breadcrumb/rh-breadcrumb.js	179 B
./react/rh-button/rh-button.js	174 B
./react/rh-card/rh-card.js	172 B
./react/rh-code-block/rh-code-block.js	181 B
./react/rh-cta/rh-cta.js	170 B
./react/rh-dialog/rh-dialog.js	203 B
./react/rh-footer/rh-footer-block.js	184 B
./react/rh-footer/rh-footer-copyright.js	187 B
./react/rh-footer/rh-footer-links.js	185 B
./react/rh-footer/rh-footer-social-link.js	193 B
./react/rh-footer/rh-footer-universal.js	188 B
./react/rh-footer/rh-footer.js	174 B
./react/rh-health-index/rh-health-index.js	184 B
./react/rh-icon/rh-icon.js	202 B
./react/rh-menu/rh-menu.js	173 B
./react/rh-navigation-secondary/rh-navigation-secondary-dropdown.js	217 B
./react/rh-navigation-secondary/rh-navigation-secondary-menu-section.js	205 B
./react/rh-navigation-secondary/rh-navigation-secondary-menu.js	199 B
./react/rh-navigation-secondary/rh-navigation-secondary-overlay.js	201 B
./react/rh-navigation-secondary/rh-navigation-secondary.js	213 B
./react/rh-pagination/rh-pagination.js	178 B
./react/rh-site-status/rh-site-status.js	181 B
./react/rh-skip-link/rh-skip-link.js	181 B
./react/rh-spinner/rh-spinner.js	175 B
./react/rh-stat/rh-stat.js	171 B
./react/rh-subnav/rh-subnav.js	175 B
./react/rh-surface/rh-surface.js	175 B
./react/rh-switch/rh-switch.js	185 B
./react/rh-table/rh-sort-button.js	213 B
./react/rh-table/rh-table.js	174 B
./react/rh-tabs/rh-tab-panel.js	181 B
./react/rh-tabs/rh-tab.js	187 B
./react/rh-tabs/rh-tabs.js	174 B
./react/rh-tag/rh-tag.js	182 B
./react/rh-tile/rh-tile-group.js	183 B
./react/rh-tile/rh-tile.js	194 B
./react/rh-timestamp/rh-timestamp.js	176 B
./react/rh-tooltip/rh-tooltip.js	175 B
./react/rh-video-embed/rh-video-embed.js	227 B

_{compressed-size-action}