docs: add missing jinja2 tags (#6136)

Co-authored-by: Gergely Bräutigam <gergely.brautigam@sap.com>

docs/snippets/certsans-template-v2-external-secret.yaml

@@ -1,3 +1,4 @@
+{% raw %}
 apiVersion: external-secrets.io/v1
 kind: ExternalSecret
 metadata:
@@ -14,3 +15,4 @@ spec:
         primary-domain: '{{ index (.certificate | filterPEM "CERTIFICATE" | filterCertChain "leaf" | certSANs) 0 }}'
         # Store SANs as a JSON array
         sans-json: '{{ .certificate | filterPEM "CERTIFICATE" | filterCertChain "leaf" | certSANs | toJson }}'
+{% endraw %}