Update registry.yaml

[paytonison]

Summary

Briefly describe the changes and the goal of this PR. Make sure the PR title summarizes the changes effectively.

Motivation

Why are these changes necessary? How do they improve the cookbook?

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For new content

When contributing new content, read through our contribution guidelines, and mark the following action items as completed:

• I have added a new entry in registry.yaml (and, optionally, in authors.yaml) so that my content renders on the cookbook website.
• I have conducted a self-review of my content based on the contribution guidelines:
  • Relevance: This content is related to building with OpenAI technologies and is useful to others.
  • Uniqueness: I have searched for related examples in the OpenAI Cookbook, and verified that my content offers new insights or unique information compared to existing documentation.
  • Spelling and Grammar: I have checked for spelling or grammatical mistakes.
  • Clarity: I have done a final read-through and verified that my submission is well-organized and easy to understand.
  • Correctness: The information I include is correct and all of my code executes successfully.
  • Completeness: I have explained everything fully, including all necessary references and citations.

We will rate each of these areas on a scale from 1 to 4, and will only accept contributions that score 3 or higher on all areas. Refer to our contribution guidelines for more details.

[Copilot]

Pull Request Overview

This PR adds a new entry to the registry.yaml file to register a new introductory article about LLMs. The change enables the new content to be rendered on the cookbook website.

• Adds registry entry for "LLMs 101: What Even Is It?" article
• Configures metadata including author, date, and tags for the new content

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