Add maintainers for LLM-D project

[riaankleinhans]

Checklist for maintainer updates

https://github.com/llm-d/llm-d/blob/main/MAINTAINERS.md

• You've provided a link to documentation where the project has approved the maintainer changes.
• The maintainer(s) also created or updated their LFX Individual Dashboard profile, Linking their Github handle to their profile
• You've sent an email with the list of email address(es) to cncf-maintainer-changes@cncf.io for invitations to Service Desk and mailing lists. You can just mark this complete if you are only removing people.
• Optional: You've also sent a PR with affiliation updates to cncf/gitdm.

[netlify]

✅ Deploy Preview for cncf-license-exceptions canceled.

Name	Link
🔨 Latest commit	643f830
🔍 Latest deploy log	https://app.netlify.com/projects/cncf-license-exceptions/deploys/6a183ed21d3c1f0008bb60cf