docs: Add sunnypurewal/a2ui-swiftui to community renderers

[sunnypurewal]

Description

I've added my SwiftUI renderer to the community renderers page. My renderer is an implementation of the v0.9 spec which is still in development. However, I noticed the significant improvements in v0.9 when building my A2UI agentic backend and wanted to make sure my implementation wasn't outdated before it was even released. I will ensure that as the v0.9 spec is finalized, my renderer keeps up with changes.

Thanks to the A2UI team and @zeroasterisk for the guidance

Issue #680

Pre-launch Checklist

• I signed the CLA.
• I read the Contributors Guide.
• I read the Style Guide.
• I have added updates to the CHANGELOG.
• I updated/added relevant documentation.
• My code changes (if any) have tests.

If you need help, consider asking for advice on the discussion board.

[gemini-code-assist]

Code Review

This pull request adds a new SwiftUI community renderer to the documentation. The change to renderers.md is correct. However, the pre-launch checklist in the pull request description indicates that CHANGELOG.md has been updated, but this file's changes are not included in the pull request. The repository's style guide requires all steps in the pre-review checklist to be completed accurately. Please either add the changelog update to this pull request or uncheck the item in the description if a changelog entry is not required for this type of change.