chore(rel): add diagram to postgres collation

Author: Jacob Pleiness

docs/admin/postgresql_collation_version_mismatch_resolution.mdx

@@ -20,6 +20,8 @@ Self-hosted customers using external databases, such as AWS RDS, GCP CloudSQL, o
 
 Sourcegraph Cloud customers are not affected.
 
+<img src="/postgres_collation_affected_customers.png" alt="Postgres collation affected customers" />
+
 # Symptoms
 
 When logging into the database via `psql` or similar tools you may see the following warning: