Theme: Include density documentation in README.md

[aduth]

What?

Updates @wordpress/theme's README.md to describe the behavior of the density prop.

Why?

• For consistency with how we're documenting color
• To clarify usage of the ThemeProvider component and its available features
• To acknowledge and capture the intended purpose of the available density options

Testing Instructions

Review proposed documentation for accuracy.

[github-actions]

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Co-authored-by: aduth <aduth@git.wordpress.org>
Co-authored-by: juanfra <juanfra@git.wordpress.org>

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[github-actions]

Flaky tests detected in 3f3d40a.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/20173375481
📝 Reported issues:

• [Flaky Test] should open and edit templates correctly when active_templates experiment is disabled #73743 in /test/e2e/specs/site-editor/template-id-format.spec.js
• [Flaky Test] should open and edit templates correctly when active_templates experiment is enabled #73752 in /test/e2e/specs/site-editor/template-id-format.spec.js

[juanfra]

LGTM ✅

[juanfra]

Nit: we might want to end these list items with a full stop, to stay consistent with the style used elsewhere.

Suggested change

	- `'default'`: Standard spacing for general use
	- `'compact'`: Reduced spacing for information-dense interfaces like data tables or dashboards
	- `'comfortable'`: Increased spacing for focused experiences like modals, dialogs, or full-screen settings panels
	- `'default'`: Standard spacing for general use.
	- `'compact'`: Reduced spacing for information-dense interfaces like data tables or dashboards.
	- `'comfortable'`: Increased spacing for focused experiences like modals, dialogs, or full-screen settings panels.

[aduth]

Could you clarify what you mean by "elsewhere" ? We're not especially consistent in this file 😅 The original proposed content follows from the color prop listing above, though there's also lists elsewhere in the file (e.g. "Building") that include periods.

I guess it's a broader question of whether we have content guidelines for this and whether they're discoverable enough.

[aduth]

There's some guidance in the documentation copy guide for bulleted lists, though it's more about consistency and less about prescribing dots or not dots.

In any case, I pushed changes in b3bb942 to make it consistent across the files: Dots at the end of list items, and no dots within tables.

[juanfra]

Fair point 😅

Before leaving the nit I just checked a couple of other readme's as a reference, like dataviews, which felt fairly up to date and uses full stops in lists.

No strong feelings either way though. But indeed, maybe it’s a sign we could use a lightweight guideline at some point (updated after you shared the copy guide)

[mirka]

I also have a preference for full stops at the end of bullet points 🙂