[docs] extension.llm.tokenizer.tokenizer is no longer valid

[kirklandsign]

📚 The doc issue

Seems that this command is no longer valid

python -m extension.llm.tokenizer.tokenizer -t tokenizer.model -o tokenizer.bin

https://github.com/search?q=repo%3Apytorch%2Fexecutorch%20extension.llm.tokenizer.tokenizer&type=code

Suggest a potential alternative/fix

No response

[lucylq]

Think this is fixed by #10000 !