Update README.md

Author: jessebot

README.md

@@ -92,5 +92,9 @@ cnpgCluster:
 
 ### Using the test app
 
-The test app may be enabled by certificates as well as setting `testApp.enabled` to `true` in the values.yaml.
+The test app may be enabled by certificates as well as setting `testApp.enabled=true` in your helm parameters or in the `values.yaml` like this:
+```yaml
+testApp:
+  enabled: true
+```
 This will create a very basic Deployment of `ghcr.io/cloudnative-pg/webtest` [as described in the official docs](https://cloudnative-pg.io/docs/1.28/ssl_connections#testing-the-connection-via-a-tls-certificate) that attempts to connect to your postgres cluster using full mTLS.