urlwatch: Allow configuration of crontab entry

[Andreas Schildbach]

Currently it appears to be hardcoded to every half hour. I would like to use an argument or environment variable to change that (without rebuilding the docker image from the dockerfile).

[K̶e̶v̶i̶n̶]

If you want to change the interval, you can mount a crontab config file.

# /path/to/your/file -> /etc/crontabs/root

*/5 * * * * cd /root/.urlwatch && urlwatch --urls urls.yaml --config urlwatch.yaml --hooks hooks.py --cache cache.db

-v /path/to/your/file:/etc/crontabs/root

[K̶e̶v̶i̶n̶]

@robgmills Thanks