feat(NavList): add support for inline and block description

[francinelucca]

Closes https://github.com/github/primer/issues/6085

Changelog

New

• "With Description" NavList story
• export ActionList.Description as a NavList subcomponent

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: d81a127

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Minor

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

[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the integration-tests: skipped manually label to skip these checks.

[Copilot]

Pull Request Overview

This PR adds support for inline and block descriptions in NavList by exporting ActionList.Description as a NavList subcomponent. This enables NavList items to display additional descriptive text in two variants: inline (beside primary text) or block (below primary text).

• Exported ActionList.Description as NavList.Description
• Added new "With Description" story demonstrating both inline and block variants
• Documented the Description component with its props in the docs.json file

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/react/src/NavList/NavList.tsx	Exports ActionList.Description as NavList.Description subcomponent
packages/react/src/NavList/NavList.features.stories.tsx	Adds comprehensive story showcasing inline and block description variants
packages/react/src/NavList/NavList.docs.json	Documents NavList.Description props and adds story reference
e2e/components/NavList.test.ts	Adds e2e test entry for the new description feature
.changeset/happy-clocks-cover.md	Documents the feature addition as a minor version change

[liuliu-dev]

✨

[primer-integration]

👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/6883

[primer-integration]

🟢 ci completed with status success.