Usage instructions for v5 beta

Added example config for v5 beta.

README.md

@@ -16,6 +16,12 @@ Install with:
 yarn add postgraphile postgraphile-plugin-connection-filter
 ```
 
+for PostGraphile v5 (beta):
+
+```
+yarn add postgraphile@beta postgraphile-plugin-connection-filter@beta
+```
+
 CLI usage via `--append-plugins`:
 
 ```
@@ -33,6 +39,20 @@ const middleware = postgraphile(DATABASE_URL, SCHEMAS, {
 });
 ```
 
+Config example for PostGraphile v5 (beta), `graphile.config.mjs`:
+
+```ts
+import ConnectionFilterPlugin from 'postgraphile-plugin-connection-filter'
+
+const preset = {
+  extends: [
+    ConnectionFilterPlugin.PostGraphileConnectionFilterPreset
+  ]
+}
+
+export default preset
+```
+
 ## Performance and Security
 
 By default, this plugin: