docs: extract theme configuration guide

[benvinegar]

Summary

• move detailed theme configuration into docs/themes.md
• keep the README configuration section focused on the basics and link to the guide

Testing

• bun run format
• bun run lint

This PR description was generated by Pi using GPT-5.2

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Project	Deployment	Actions	Updated (UTC)
hunk-web	Ready	Preview	Jul 28, 2026 2:41pm

[greptile-apps]

Greptile Summary

This PR extracts the detailed theme configuration guide from the README.

• Adds docs/themes.md covering automatic selection, custom themes, syntax scopes, and legacy migration.
• Replaces the detailed README section with a focused overview and a valid link to the new guide.
• Adds an intentionally empty changeset for the documentation-only update.

Confidence Score: 5/5

The documentation-only PR appears safe to merge.

The extracted guide preserves the previous instructions, the README link resolves correctly, documented theme behavior matches the implementation, and the empty changeset follows repository conventions.

Important Files Changed

Filename	Overview
README.md	Condenses theme configuration documentation and links to the extracted guide without losing essential guidance.
docs/themes.md	Preserves the prior theme documentation in a focused guide whose examples and behavior match the current implementation.
.changeset/twelve-dancers-marry.md	Adds an empty changeset consistent with the repository convention for documentation-only maintenance.

_{Reviews (1): Last reviewed commit: "docs: move theme configuration guide" | Re-trigger Greptile}