Add slack example

examples/slack/Dockerfile

@@ -0,0 +1,17 @@
+FROM python:3.11.3-slim-buster
+WORKDIR /app/
+COPY requirements.txt /app/
+
+RUN apt-get update && apt-get install build-essential git -y
+RUN pip install -U pip && pip install -r requirements.txt
+COPY *.py /app/
+COPY *.sh /app/
+RUN mkdir /app/app/
+COPY app/*.py /app/app/
+ENTRYPOINT /app/entrypoint.sh
+
+# docker build . -t your-repo/chat-gpt-in-slack
+# export SLACK_APP_TOKEN=xapp-...
+# export SLACK_BOT_TOKEN=xoxb-...
+# export OPENAI_API_KEY=sk-...
+# docker run -e SLACK_APP_TOKEN=$SLACK_APP_TOKEN -e SLACK_BOT_TOKEN=$SLACK_BOT_TOKEN -e OPENAI_API_KEY=$OPENAI_API_KEY -it your-repo/chat-gpt-in-slack