[doc] Fix tokenizer related documentation (#10000)

`extension.llm.tokenizer.tokenizer` ->
`pytorch_tokenizers.tools.llama2c.convert`

Author: larryliu0820

examples/demo-apps/android/LlamaDemo/docs/delegates/qualcomm_README.md

@@ -135,7 +135,7 @@ You may also wonder what the "--metadata" flag is doing. This flag helps export
 
 Convert tokenizer for Llama 2
 ```
-python -m extension.llm.tokenizer.tokenizer -t tokenizer.model -o tokenizer.bin
+python -m pytorch_tokenizers.tools.llama2c.convert -t tokenizer.model -o tokenizer.bin
 ```
 Rename tokenizer for Llama 3 with command: `mv tokenizer.model tokenizer.bin`. We are updating the demo app to support tokenizer in original format directly.
 

examples/models/llama2/README.md

@@ -41,7 +41,7 @@ You can export and run the original Llama 2 7B model.
     ```
 4. Create tokenizer.bin.
     ```
-    python -m extension.llm.tokenizer.tokenizer -t <tokenizer.model> -o tokenizer.bin
+    python -m pytorch_tokenizers.tools.llama2c.convert -t <tokenizer.model> -o tokenizer.bin
     ```
 
     Pass the converted `tokenizer.bin` file instead of `tokenizer.model` for subsequent steps.

examples/models/phi-3-mini/README.md

@@ -13,7 +13,7 @@ pip uninstall -y transformers ; pip install transformers==4.44.2
 ```
 cd executorch
 wget -O tokenizer.model "https://huggingface.co/microsoft/Phi-3-mini-128k-instruct/resolve/main/tokenizer.model?download=true"
-python -m extension.llm.tokenizer.tokenizer -t tokenizer.model -o tokenizer.bin
+python -m pytorch_tokenizers.tools.llama2c.convert -t tokenizer.model -o tokenizer.bin
 ```
 2. Export the model. This step will take a few minutes to finish.
 ```

examples/qualcomm/oss_scripts/llama/README.md

@@ -41,7 +41,7 @@ wget "https://huggingface.co/karpathy/tinyllamas/resolve/main/stories110M.pt"
 wget "https://raw.githubusercontent.com/karpathy/llama2.c/master/tokenizer.model"
 
 # tokenizer.bin:
-python -m extension.llm.tokenizer.tokenizer -t tokenizer.model -o tokenizer.bin
+python -m pytorch_tokenizers.tools.llama2c.convert -t tokenizer.model -o tokenizer.bin
 
 # params.json:
 echo '{"dim": 768, "multiple_of": 32, "n_heads": 12, "n_layers": 12, "norm_eps": 1e-05, "vocab_size": 32000}' > params.json