docs: add us-east-2 to Edge Functions regional invocation page

The Available regions list enumerated every region enabled in the
edge-runtime Pulumi regionConfig except us-east-2 (Ohio), so readers
choosing a region for an Edge Function had no way to know Ohio was
available.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017UJhSvVpPfYNaHZ8Y1x3sy

Co-authored-by: Lakshan Perera <5358+laktek@users.noreply.github.com>

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

@@ -31,6 +31,7 @@ The following regions are supported:
 
 - `ca-central-1` (Canada Central)
 - `us-east-1` (N. Virginia)
+- `us-east-2` (Ohio)
 - `us-west-1` (N. California)
 - `us-west-2` (Oregon)