Update README.md

Author: zachary62

README.md

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 This is a tutorial project of [Pocket Flow](https://github.com/The-Pocket/PocketFlow), a 100-line LLM framework. It crawls GitHub repositories and build a knowledge base from the code. It analyzes entire codebases to identify core abstractions and how they interact, and transforms complex code into beginner-friendly tutorials with clear visualizations.
 
+- Check out the [Substack Post](https://zacharyhuang.substack.com/p/ai-codebase-knowledge-builder-full) for more!
+
 ## ⭐ Example Tutorials for Popular GitHub Repositories!
 
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