Update system-requirements.mdx (#3327)

Clarify Postgres version recommendation

website/content/docs/install-boundary/system-requirements.mdx

@@ -119,7 +119,7 @@ This also means that you can use a simple layer 4 load balancer to pass through
 ## Database recommendations
 
 Boundary clusters depend on a PostgreSQL database for managing state and configuration.
-Boundary has only been tested on PostgreSQL 11 or greater.
+Ensure you are using a version of PostgreSQL covered under [Boundary's supported version policy](https://developer.hashicorp.com/boundary/docs/enterprise/supported-versions#postgresql-support-policy).
 
 Each major cloud provider offers a managed PostgreSQL database service:
 
@@ -169,4 +169,4 @@ Each major cloud provider offers one or more managed load balancing services:
 | GCP | Network/Application | 4/7 | [Cloud load balancing](https://cloud.google.com/load-balancing/docs/load-balancing-overview) |
 
 Boundary workers do not require any load balancing.
-Load balancing for the Boundary workers is handled by the Boundary controllers when clients initiate sessions to Boundary targets.
+Load balancing for the Boundary workers is handled by the Boundary controllers when clients initiate sessions to Boundary targets.