Force shared_buffers size to 512MB

For some reason it was at 8MB by default when it was supposed to be
128MB.

admin/README.md

@@ -200,6 +200,11 @@ From the webUI or following longhorn's current instructions we can change most
 if not all of these settings. If a cluster with one node has more nodes added
 on in the future you may want to consider increasing the replicate count.
 
+NOTE: The web UI does **NOT** have authentication by default. It must be
+      configured manually. See
+      https://longhorn.io/docs/1.0.0/deploy/accessing-the-ui/longhorn-ingress/
+      for more information.
+
 ### Storage - Local Large Cache
 
 **DEPRECATED**: See local path provisioner above.

ci_geosphere/values-postgis.yaml

 postgresqlDatabase: "postgres"
+postgresqlConfiguration:
+  sharedBuffers: "512MB"
 persistence:
   enabled: true
   existingClaim: "geosphere-postgis"