doc(README): adapt warning blockquote

This reverts commit 98fe8fe2a4.

.drone.yml

@@ -26,7 +26,7 @@ steps:
 - name: markdown lint
   commands:
   - markdownlint *.md
-  image: git.cryptic.systems/volker.raschek/markdownlint:0.41.0
+  image: git.cryptic.systems/volker.raschek/markdownlint:0.42.0
   resources:
     limits:
       cpu: 150

README.md

@@ -66,9 +66,9 @@ The following examples serve as individual configurations and as inspiration for
 The first example shows how to deploy the metric exporter with TLS encryption. The verification of the custom TLS
 certification will be skipped by Prometheus.
 
-> [!WARN]
-> A TLS secret with the name `prometheus-postgresql-exporter-http` containing a `ca.crt`, `tls.key` and `tls.crt` is
-> already present.
+> [!WARNING]
+> The secret `prometheus-postgresql-exporter-http` containing the TLS certificate is already present. The keys `ca.crt`,
+> `tls.key` and `tls.crt` of the secret can be mounted into the container filesystem for TLS authentication / encryption.
 
 ```bash
 helm install prometheus-exporters/prometheus-postgres-exporter prometheus-postgres-exporter \