Add Docker Compose setup guide.

[tranhd95]

Hi, I needed to restrict the public access of my Pipelines instance running in a Docker container on my VPS. Figured out that the simplest way is to run both Open WebUI and Pipelines through Docker compose which handles the networking and we can restrict the access just to the Open WebUI container (service) without need to publish the port to the host and using --add-host=host.docker.internal:host-gateway.

Added an example docker-compose.yaml file and relevant guide in the README.md.

[ezavesky]

Hi @tranhd95 -- thanks, this helped me to get started! May I suggest a few additional tweaks so that the local version is aware of the docker-compose version? These modifications will turn off authentication on your local OpenWebUI container and make sure the pipeline instance is auto-configured. Also, if you're adding a new file in the repo maybe you can just refer to that in the README instead of repeating the stanzas and have two places to update. Thanks again!

Under the 'services' chunk that creates the local OpenWebUI container

  environment:
      WEBUI_AUTH: False
      WEBUI_NAME: Local Test
      ENABLE_SIGNUP: False
      ENABLE_OLLAMA_API: False
      OPENAI_API_BASE_URLS: http://pipelines:9099;
      OPENAI_API_KEYS: 0p3n-w3bu!;

Under the 'pipelines' chunk that creates the local pipelines container

 environment:
      PIPELINES_API_KEY: 0p3n-w3bu!
      RESET_PIPELINES_DIR: False