Move L&R calendar under the main setup actions

Why is this change being made?

Currently the page has a note about L&R calendars, but its placement makes it seem like all the one-time-setup steps should only be done by L&R folks. This MR moves the note farther down so it's clear that it's just one other step/option in your calendar setup.

https://about.gitlab.com/handbook/support/support-time-off.html#support-time-off-calendars

Author Checklist

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