Merge pull request #371 from CybercentreCanada/container-build-options

clarify comment

Dockerfile

@@ -17,7 +17,7 @@ RUN apt-get update \
   && rm -rf /var/lib/apt/lists/*
 
 # Install assemblyline base (setup.py is just a file we know exists so the command
-# won't fail. The dist* copies in any dist directory only if it exists.)
+# won't fail if dist isn't there. The dist* copies in any dist directory only if it exists.)
 COPY setup.py dist* dist/
 RUN pip install --no-cache-dir -f dist/ --user assemblyline==$version && rm -rf ~/.cache/pip