docs: add eu-central-2 to Edge Functions regional invocation page (#48721)

<!-- ccr-slack-attribution -->
_Requested by **Kalleby Santos** · [Slack
thread](https://supabase.slack.com/archives/C02KMRX22NR/p1785871243937099?thread_ts=1785871243.937099&cid=C02KMRX22NR)_

## I have read the
[CONTRIBUTING.md](https://github.com/supabase/supabase/blob/master/CONTRIBUTING.md)
file.

YES

## What kind of change does this PR introduce?

Docs update — one-line content fix.

## What is the current behavior?

The [Regional
Invocations](https://supabase.com/docs/guides/functions/regional-invocation)
page's "Available regions" section lists every Edge Functions region
**except `eu-central-2`** (AWS Europe, Zurich). The region has been live
in production for a while, but it was never added to the docs. A user
reading this page to pick a region for `x-region` / `FunctionRegion` had
no way to know Zurich was an option — the page reads as an exhaustive
list, so the omission actively implies the region doesn't exist.

Reported by Kalleby Santos (Edge Functions team).

Linear: [FUNC-761 — Add eu-central-2 to regional invocation docs
page](https://linear.app/supabase/issue/FUNC-761/add-eu-central-2-to-regional-invocation-docs-page)

## What is the new behavior?

**Before:** the Europe group listed `eu-central-1`, `eu-west-1`,
`eu-west-2`, `eu-west-3`.

**After:** `eu-central-2` (Zurich) is listed alongside the others, so
the page reflects the regions Edge Functions actually serves.

### How

One line added to
`apps/docs/content/guides/functions/regional-invocation.mdx`, in the
**Europe** group directly after `eu-central-1`, following the list's
existing sort-by-region-code order and the surrounding `` `code` (Short
location) `` label style:

```diff
 **Europe:**

 - `eu-central-1` (Frankfurt)
+- `eu-central-2` (Zurich)
 - `eu-west-1` (Ireland)
 - `eu-west-2` (London)
 - `eu-west-3` (Paris)
```

No other files changed. This page's region list is hand-maintained in
the MDX and is deliberately narrower than the project-creation region
list in `packages/shared-data/regions.ts` (which also includes
`us-east-2` and `eu-north-1`), so no shared constant needed updating and
no other product's region list was touched.

## Additional context

**Verification that `eu-central-2` is a real Edge Functions invocation
region** — confirmed in three independent places:

1. `supabase/platform` → `pulumi/edge-runtime/Pulumi.prod.yaml:533` —
`region: eu-central-2`, with `enabled: true` at `:531`. A fully
provisioned prod region (360–540 always-on tasks), not a placeholder.
Branch `develop`, HEAD `1f44167768f951c0c794313006bc2c9f9758c344`.
2. `supabase/platform` →
`pulumi/edge-runtime-next/stack-config/Pulumi.prod.aws.euc2.yaml:6` —
`aws:region: eu-central-2` under the `Edge-Functions/K8s-Prod`
environment, tagged `product: functions`.
3. `supabase/api-gateway` → `customer-router/wrangler.toml` —
`eu-central-2` is present in the `EDGE_FUNCTIONS_REGIONAL_ORIGINS` map
(`eu-central-2 = "https://eu-central-2.edge-runtime.supabase.green"`).
This is the table that resolves the `x-region` header, so regional
invocation into Zurich is genuinely routable — not just deployed.

**For a reviewer to confirm separately (intentionally not in this
diff):** production infra has 16 enabled Edge Functions regions, so
`us-east-2` (Ohio, `pulumi/edge-runtime/Pulumi.prod.yaml:507`, `enabled:
true`) is *also* missing from this page. It's excluded here because we
don't yet know whether that omission is deliberate; it's being confirmed
with the team and can be a follow-up.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_017UJhSvVpPfYNaHZ8Y1x3sy

---
_Generated by [Claude
Code](https://claude.ai/code/session_017UJhSvVpPfYNaHZ8Y1x3sy)_

Co-authored-by: Claude <noreply@anthropic.com>

apps/docs/content/guides/functions/regional-invocation.mdx

@@ -37,6 +37,7 @@ The following regions are supported:
 **Europe:**
 
 - `eu-central-1` (Frankfurt)
+- `eu-central-2` (Zurich)
 - `eu-west-1` (Ireland)
 - `eu-west-2` (London)
 - `eu-west-3` (Paris)