docs(content-header): add ux styleguide

[katjaKoppensteiner]

💡 What is the current behavior?

No UX documentation for Content Header

IX-502

🆕 What is the new behavior?

UX documentation for Content header

🏁 Checklist

A pull request can only be merged if all of these conditions are met (where applicable):

• 🦮 Accessibility (a11y) features were implemented
• 🗺️ Internationalization (i18n) - no hard coded strings
• 📲 Responsiveness - components handle viewport changes and content overflow gracefully
• 📄 Documentation was reviewed/updated (pnpm run docs)
• 🧪 Unit tests were added/updated and pass (pnpm test)
• 📸 Visual regression tests were added/updated and pass (Guide)
• 🧐 Static code analysis passes (pnpm lint)
• 🏗️ Successful compilation (pnpm build, changes pushed)

👨‍💻 Help & support

[changeset-bot]

⚠️ No Changeset found

Latest commit: e756559

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