add readme files

ch01/README.md

@@ -1,2 +1,3 @@
-Details will follow ...
+# Chapter 1: Understanding Large Language Models
 
+There is no code in this chapter.

ch02/01_main-chapter-code/README.md

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+# Chapter 2: Working with Text Data
+
+- [ch02.ipynb](ch02.ipynb) has all the code as it appears in the chapter
+- [dataloader.ipynb](dataloader.ipynb) is a minimal notebook with the main data loading pipeline implemented in this chapter
+

ch02/02_bonus_bytepair-encoder/README.md

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+# Chapter 2: Working with Text Data
+
+
+
+- [compare-bpe-tiktoken.ipynb](compare-bpe-tiktoken.ipynb) benchmarks various byte pair encoding implementations
+- [bpe_openai_gpt2.py](bpe_openai_gpt2.py) is the original bytepair encoder code used by OpenAI
+

ch02/03_bonus_embedding-vs-matmul/README.md

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+# Chapter 2: Working with Text Data
+
+- [embeddings-and-linear-layers.ipynb](embeddings-and-linear-layers.ipynb) contains optional (bonus) code to explain that embedding layers and fully connected layers applied to one-hot encoded vectors are equivalent.

ch02/README.md

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+# Chapter 2: Working with Text Data
+
+- [01_main-chapter-code](01_main-chapter-code) contains the main chapter code
+  
+- [02_bonus_bytepair-encoder](02_bonus_bytepair-encoder) contains optional code to benchmark different byte pair encoder implementations
+  
+- [03_bonus_embedding-vs-matmul](03_bonus_embedding-vs-matmul) contains optional (bonus) code to explain that embedding layers and fully connected layers applied to one-hot encoded vectors are equivalent.