Add 4 AI engineering newsletters

[conorbronsdon]

Adds four newsletters to Newsletters > Commentators/ML Eng's, all written by individual practitioners. Placed in roughly alphabetical order to match the section.

• Chip Huyen's blog (https://huyenchip.com/blog/) - in-depth essays on AI system design from the author of O'Reilly's AI Engineering.
• Chain of Thought (https://newsletter.chainofthought.show/) - interviews and writeups on agents, evals, and LLMOps. Disclosure: this is my newsletter.
• Hamel Husain's blog (https://hamel.dev/) - hands-on writeups on LLM evals, error analysis, and shipping AI products.
• Simon Willison's newsletter (https://simonw.substack.com/) - prolific practical commentary on LLMs, tooling, and prompt injection from the Datasette creator.

All four are active in 2026 and none were already on the list. Single-line entries matching the neighboring format.