Organized setup instructions (#115)

* Organized setup instructions

* update tets

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* raise error upon broken link

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* delete duplicated paragraph

setup/03_optional-docker-environment/.devcontainer/Dockerfile

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+FROM pytorch/pytorch:2.0.1-cuda11.7-cudnn8-runtime
+
+RUN apt-get update && \
+    apt-get upgrade -y && \
+    apt-get install -y rsync && \
+    apt-get install -y git && \
+    rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt requirements.txt
+
+RUN pip install --no-cache-dir -r requirements.txt