fix header depth

Author: sbernauer

docs/modules/secret-operator/pages/secretclass.adoc

@@ -39,7 +39,7 @@ CAUTION: Attributes of the certificate (such as the expiration date, fingerprint
 xref:scope.adoc[Scopes] are used to populate the claims (such as `subjectAlternateName`) of the provisioned certificates.
 
 [#backend-tls-certificate-key-pair-generation]
-=== `TLS certificate key pair generation`
+==== `TLS certificate key pair generation`
 
 Currently, only RSA is supported in the `autoTls` backend.
 You can however configure the key length for generated private keys. If not specified it will default to `2048` bits.