Add RubyLLM instrumentation to registry

[clarissalimab]

• I have read and followed the Contributing docs, especially the "First-time contributing?" section.
• This PR has content that I did not fully write myself.
  • I used AI and I have read and followed the Generative AI Contribution Policy.
• I have the experience and knowledge necessary to understand, review, and validate all content in this PR.¹

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Adds registry entry for opentelemetry-instrumentation-ruby_llm, a Ruby instrumentation library for tracing LLM interactions via RubyLLM.

Footnotes

1. Yes, I can answer maintainer questions about the content of this PR, without using AI. ↩

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: clarissalimab / name: Clarissa Borges (e688783)

[clarissalimab]

/fix:refcache

[otelbot-docs]

❌ fix:refcache failed or exited with a non-zero error code (0). See logs: https://github.com/open-telemetry/opentelemetry.io/actions/runs/21830895848