message: Update INSTALL.md with python requirements
diff: @@ -13,6 +13,10 @@ git clone --recursive https://github.com/flexflow/flexflow-third-party.git
  git clone https://github.com/flexflow/FlexFlow.git
  ```
  +# FlexFlow Python dependencies
  +* The FlexFlow Python support requires several additional Python libraries, please check [this](https://github.com/flexflow/FlexFlow/blob/master/python/requirements.txt) for details.
  +We recommend to use `pip` or `conda` to install the dependencies.
  +
  # Build the FlexFlow
  ## Makefile
  ### Build FlexFlow Runtime
  @@ -90,7 +94,8 @@ cd config
  ```
  The `config.linux` is an example of how to set the varibles required for CMake build. Please modify `CUDA_ARCH`, `CUDNN_DIR`, `LEGION_DIR` and `PROTOBUF_DIR` according to your environment. `LEGION_DIR` and `PROTOBUF_DIR` are the installation directories of Legion and Protocol Buffer, not the source code directories.
  -Then go to the home directory of FlexFlow, and run
  +
  +Once the variables in the `config.linux` is set correctly, go to the home directory of FlexFlow, and run
  ```
  mkdir build
  cd build
  