Increase periodic docs build interval from 30 minutes to 3 hours

[reakaleek]

What

• Increase the periodic docs build cron schedule from every 30 minutes to every 3 hours

Why

• Reduce unnecessary build frequency and resource usage for periodic docs builds

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[KOTungseth]

I have a post it on my desk that says we discussed, "cron change from 1 hour to 1 day." 3 hours is fine, but I'm double checking.

[karenzone]

@KOTungseth, we have the ability to kick off a manual build if we need it, so expanding the time between builds is a win no matter how we set the schedule. 🎉

[reakaleek]

We can still decide to increase the cron in a follow-up. But I will merge this.. otherwise the queue will pile up again.