Add minor commenting

Dockerfile

@@ -1,6 +1,7 @@
 FROM python:3.6-slim
 
 RUN apt-get update
+# OpenCV has a LOT of dependencies.
 RUN apt-get install -y \
     libglib2.0-0 \
     libsm6 \
@@ -23,7 +24,7 @@ WORKDIR /app
 COPY . /app
 
 # We aren't listening, just connecting, so probs won't need this.
-EXPOSE 1883
+# EXPOSE 1883
 ENV PYTHONPATH=/app
 
 CMD ["python", "DecisionSystem/CentralisedDecision/cameraserver.py", "-V", "/app/HandRecognitionMacbookFixed.mp4"]