docs: document that HCP Vault Secrets free-tier is not supported (kroxylicious#2914)

Author: k-wall

kroxylicious-docs/docs/record-encryption-guide/index.adoc

@@ -23,7 +23,7 @@ To use the filter, follow these steps:
 The filter integrates with a Key Management Service (KMS), which is responsible for the safe storage of sensitive key material.
 Kroxylicious supports the following KMS providers:
 
-* HashiCorp Vault
+* HashiCorp Vault (On-premise, HashiCorp Cloud Platform Vault and Enterprise are supported. Free tier HCP Vault Secrets is not).
 * AWS Key Management Service.
 ifdef::include-fortanix-dsm-kms[]
 * Fortanix DSM
@@ -49,4 +49,4 @@ include::_assemblies/assembly-monitoring-record-encryption-filter.adoc[leveloffs
 include::_assemblies/assembly-operations-record-encryption-filter.adoc[leveloffset=+1]
 
 //trademark notices
-include::_assets/trademarks.adoc[leveloffset=+1]
+include::_assets/trademarks.adoc[leveloffset=+1]