Comments added

Dockerfile

@@ -1,9 +1,13 @@
+# Derive docker image from debian base image
 FROM debian
 
+# update package cache and isntall python 3 as well as pip 3
 RUN apt-get update && apt-get install -y \
     python3 \
     python3-pip
 
+# Install the module necessary for virtual environments
 RUN pip3 install virtualenv
 
+# Use bash as entry point for the container
 CMD ["/bin/bash"]