Update documentation (#2)

README.md

@@ -1,3 +1,10 @@
-# glvd-postgres
+# Garden Linux Vulnerability Database - PostgreSQL
 
-Build the postgresql container for the GLVD security tracker. For the security tracker we needed the postgres extension `debversion`, which is added here to the docker.io postgres container.
+This repository contains the container configuration for the PostgreSQL of `glvd`. The Security Tracker does not use the default PostgreSQL container but a custom one which has some extenions and configuration installed. This container is based on the PostgreSQL contaienr from `docker.io`.
+
+The following extensions and configurations have been adjusted for this PostgreSQL container:
+
+| Name | Type | Description |
+|------|------|-------------|
+| `debversion` | extension | Debian version numbers, used to version Debian binary and source packages |
+| `random_page_cost` | configuration | Sets the planner's estimate of the cost of a non-sequentially-fetched disk page. The default is 4.0. The Garden Linux Security Tracker sets this to `1.1` |