chore(rel): add diagram to postgres collation (#1177)

Add diagram to Postgres collation page

![CleanShot 2025-06-06 at [email protected]](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/K3MYHn2Q3eteSMxu0NpS/d48a6053-be20-4ec0-8a9a-130e712960c0.png)

## Pull Request approval

You will need to get your PR approved by at least one member of the Sourcegraph team. For reviews of docs formatting, styles, and component usage, please tag the docs team via the #docs Slack channel.

Author: jdpleiness

docs/admin/postgresql_collation_version_mismatch_resolution.mdx

@@ -20,6 +20,12 @@ Self-hosted customers using external databases, such as AWS RDS, GCP CloudSQL, o
 
 Sourcegraph Cloud customers are not affected.
 
+<Accordion title="Flowchart of Affected Customers">
+
+<img src="/postgres_collation_affected_customers.png" alt="Postgres collation affected customers" />
+
+</Accordion>
+
 # Symptoms
 
 When logging into the database via `psql` or similar tools you may see the following warning: