Add model, custom nodes in Dockerfile

[hongminpark]

I added models, custom nodes like this in Dockerfile. It would be better if there's any documentation for those who need to add models.

• Make directory, place model files under root directory, models/~

ADD models/controlnet/control_v11p_sd15_openpose.pth models/controlnet/

# Install custom nodes
RUN git clone https://github.com/ltdrdata/ComfyUI-Manager /comfyui/custom_nodes/ComfyUI-Manager
WORKDIR /comfyui/custom_nodes/ComfyUI-Manager
RUN pip3 install -r requirements.txt

RUN git clone https://github.com/ltdrdata/ComfyUI-Impact-Pack /comfyui/custom_nodes/ComfyUI-Impact-Pack
WORKDIR /comfyui/custom_nodes/ComfyUI-Impact-Pack
RUN pip3 install -r requirements.txt

[TimPietrusky]

@hongminpark we updated the documentation to make this more clear. Does this work for you or do you want other information?