text: Title: [DOC-FIX] Broken Links on 'Download This Notebook' Button
  Body: ### Willingness to contribute
  
  Yes. I would be willing to contribute a document fix with guidance from the MLflow community.
  
  ### URL(s) with the issue
  
  https://mlflow.org/docs/latest/llms/langchain/notebooks/langchain-retriever.html
  https://mlflow.org/docs/latest/llms/langchain/notebooks/langchain-quickstart.html
  https://mlflow.org/docs/latest/llms/transformers/tutorials/fine-tuning/transformers-peft.html
  https://mlflow.org/docs/latest/llms/openai/notebooks/openai-chat-completions.html
  
  ### Description of proposal (what needs changing)
  
  The URLs should be as follows:
  
  - **Old URL:** `https://raw.githubusercontent.com/mlflow/mlflow/master/docs/source/...`
  - **New URL:** `https://raw.githubusercontent.com/mlflow/mlflow/master/docs/docs/...`
  
  Note: The [script used to generate the button links](https://github.com/mlflow/mlflow/blob/5e67f785929e024af0504fefdd9b314896a75733/docs/scripts/convert-notebooks.py#L68) appears to be correct.
  