Add release highlights for 6.3

[edonehoo]

Add 6.3 release highlights, including summaries of completed initiatives, or significant progress updates.

Include:

• Animations update
• React 19 support
• Significant new features or docs
  • PatternFly AI (updates to high level guidelines to align with LS)
  • CLI guidelines
  • What else? (check with platform team)
• Significant bug fixes? Or code changes that requires consumer action (check with platform team)
• PatternFly 6 enablement update (check with enablement team)?

Not ready to share (wait until there's a clearer deliverable/story to share)

• Code connect - wait till complete
• Design guidelines/Figma component audit - wait till complete
• IA study - wait till results implemented
• high contrast theme - wait till we fully support

Don't seem like what we want in our highlights

• Team strategy things (PatternFly metrics, Why PatternFly, Define/know our users) - maybe in newsletter
  • Infrastructure/astro