Expose the secret EXAMPLE at buildtime

Dockerfile

@@ -7,7 +7,7 @@ RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt
 
 COPY ./main.py /code/app/main.py
 
-# Secret EXAMPLE to py
+# Secret EXAMPLE (at buildtime only)
 #RUN --mount=type=secret,id=EXAMPLE,mode=0444,required=true export EXAMPLE=$(cat /run/secrets/EXAMPLE)
 #ENV EXAMPLE=$EXAMPLE