docs(container): 📝 add docker command to include env variables on run

backend/src/main/docker/Dockerfile.jvm

@@ -13,6 +13,10 @@
 #
 # docker run -i --rm -p 8080:8080 quarkus/backend-jvm
 #
+# TO PASS IN ENV VARIABLES ON RUNNING THE CONTAINER, USE:
+#
+# docker run -i --env-file .env --rm -p 8080:8080 quarkus/backend-jvm
+#
 # If you want to include the debug port into your docker image
 # you will have to expose the debug port (default 5005 being the default) like this :  EXPOSE 8080 5005.
 # Additionally you will have to set -e JAVA_DEBUG=true and -e JAVA_DEBUG_PORT=*:5005