Update Dockerfile

Dockerfile

@@ -15,10 +15,9 @@ RUN apt-get update \
     && rm -rf /var/lib/apt/lists/* \
     && mkdir /papermc \
     && mkdir /backup
-RUN crontab -l > mycron \
-	&& echo "59 05 * * * screen -r mc -p 0 -X stuff "save-off^M"" >> mycron \
-	&& crontab mycron \
-	&& rm mycron
+RUN (crontab -l 2>/dev/null; echo "59 5 * * * screen -r mc -p 0 -X stuff "save-off^M"") | crontab -
+RUN (crontab -l 2>/dev/null; echo "59 6 * * * screen -r mc -p 0 -X stuff "save-on^M"") | crontab -
+
 
 # Start script
 CMD ["sh", "./papermc.sh"]