Remove misleading crontab guru suggestion from docs

[wez]

Since the underlying syntax is non-standard, it is very confusing and misleading to suggest using a tool with different syntax!

[qwerty287]

Is there an alternative that supports our format?

[zc-devs]

https://sysctl.io/crontab-generator
https://www.freeformatter.com/cron-expression-generator-quartz.html
https://www.programmertools.online/generator/cron_expression.html

[qwerty287]

Your first link gives me a 404, and the others are not our format I think.

They're the "quartz" format and see https://github.com/robfig/cron?tab=readme-ov-file#background---cron-spec-format, the default for our cron scheduler is standard cron, but just with seconds added.
quartz adds some more things I think, e.g. year. Also, it looks like we don't have the ?.

I found https://www.freetool.dev/crontab-generator which seems to use exactly our format but it has ads and trackers unfortunately.

Or https://bradymholt.github.io/cRonstrue which is open source but it only supports creating a readable string from a cron and not the other way.

[qwerty287]

To be honestly I think it would be the best to disable seconds in the cron completely as it makes it same to the linux standard format. But that would be a breaking change…

EDIT: Just did that in #3785 - let's continue discussion there for this topic.

[zc-devs]

Your first link gives me a 404

Yeah, it is working in my general browser (maybe cached), but not working in other or in incognito. I hope it is temporary issue.
Anyway, it is self-hosted it-tools project. The same is deployed at https://it-tools.tech/.

[qwerty287]

Ah, yes thanks works for me there (https://it-tools.tech/crontab-generator). This seems fine too. @wez Can you update the link to it?

[woodpecker-bot]

Deployment of preview was successful: https://woodpecker-ci-woodpecker-pr-3781.surge.sh