text: Title: [Usage]: Clean up Engine Args & Documentation
  Body: ### Your current environment
  
  Currently vLLM has a lot of engine arguments listed here https://docs.vllm.ai/en/latest/serving/engine_args.html. Over time as we add more and more features to vLLM, this list will be less maintainable and user friendly.
  
  
  
  ### How would you like to use vllm
  
  As a first step to clean up these args, they should be made **hierarchical** (for example, `--compilation-config`).
  
  The documentation should also be updated so that engine arg documentations are **arranged in sections instead of in a flatten list**.
  
  
  ### Before submitting a new issue...
  
  - [x] Make sure you already searched for relevant issues, and asked the chatbot living at the bottom right corner of the [documentation page](https://docs.vllm.ai/en/latest/), which can answer lots of frequently asked questions.