doc/Update service_registration if use Vault HA (#19920)

* Update service_registration if use Vault HA

* Update protocol

* Minor updates for style consistency

---------

Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com>

website/content/docs/configuration/service-registration/consul.mdx

@@ -21,12 +21,23 @@ a default health check. When Consul is configured as the storage backend, the st
 - **HashiCorp Supported** – Consul Service Registration is officially supported
   by HashiCorp.
 
+## Configuration
+
 ```hcl
 service_registration "consul" {
   address      = "127.0.0.1:8500"
 }
 ```
 
+If Vault is running in HA mode, include the transfer protocol (`http://` or
+`https://`) in the address:
+
+```hcl
+service_registration "consul" {
+  address      = "http://127.0.0.1:8500"
+}
+```
+
 Once properly configured, an unsealed Vault installation should be available and
 accessible at: