docs(search): update a11y docs

[cdransf]

Description

Improving the accessibility documentation of components.

Related issue(s)

SWC-402

Author's checklist

• I have read the CONTRIBUTING and PULL_REQUESTS documents.
• I have reviewed at the Accessibility Practices for this feature, see: Aria Practices
• I have added automated tests to cover my changes.
• I have included a well-written changeset if my change needs to be published.
• I have included updated documentation if my change required it.

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Reviewer's checklist

• Includes a Github Issue with appropriate flag or Jira ticket number without a link
• Includes thoughtfully written changeset if changes suggested include patch, minor, or major features
• Automated tests cover all use cases and follow best practices for writing
• Validated on all supported browsers
• All VRTs are approved before the author can update Golden Hash

Device review

• Did it pass in Desktop?
• Did it pass in (emulated) Mobile?
• Did it pass in (emulated) iPad?

[changeset-bot]

⚠️ No Changeset found

Latest commit: e1c005c

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[github-actions]

📚 Branch Preview

• Documentation Site
• Storybook

🔍 Visual Regression Test Results

When a visual regression test fails (or has previously failed while working on this branch), its results can be found in the following URLs:

• Spectrum | Light | Medium | LTR
• Spectrum | Dark | Large | RTL
• Express | Light | Medium | LTR
• Express | Dark | Large | RTL
• Spectrum-two | Light | Medium | LTR
• Spectrum-two | Dark | Large | RTL
• High Contrast Mode | Medium | LTR

Deployed to Azure Blob Storage: pr-5709

If the changes are expected, update the current_golden_images_cache hash in the circleci config to accept the new images. Instructions are included in that file.
If the changes are unexpected, you can investigate the cause of the differences and update the code accordingly.

[github-actions]

Tachometer results

Currently, no packages are changed by this PR...

[rise-erpelding]

This looks great! Nice work! 🌟

[caseyisonit]

nit: should this just be "Label" or "Label/placeholder"? search term isnt really a part but an value from an action. could be overthinking it

Also can we remove "A" and "An" since its a bulleted list?

[caseyisonit]

Suggested change

	Search fields come in four different sizes for mobile and desktop platform scales: small, medium, large, and extra-large. The medium size is the default and most frequently used option.
	Search fields come in four different sizes for mobile and desktop platform scales: `small`, `medium`, `large`, and `extra-large`.
	The default and most frequently used size is `medium`.