[PLA-190] chore: add eu-central-2 with 'coming soon' to region list

[BROngineer]

Description

This PR adds new region eu-central-2 (coming soon) to the region list.

Links

Fixes #[insert issue link, if any]

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[github-actions]

Allow 10 minutes from last push for the staging site to build. If the link doesn't work, try using incognito mode instead. For internal reviewers, check web-documentation repo actions for staging build status. Link to build for this PR: http://docs-dev.timescale.com/docs-artem-new-region-eu-central-2-zurich

[atovpeko]

If you don't mind, I'll hold on to this until the new region is released for sure, and then merge without the coming soon part. (We generally avoid teasing new things in case something goes wrong).