Add local flag to docs for API endpoints. (#2625)

website/source/api/system/audit.html.md

@@ -71,6 +71,13 @@ single word name or a more complex, nested path.
 
 - `type` `(string: <required>)` – Specifies the type of the audit backend.
 
+Additionally, the following options are allowed in Vault open-source, but
+relevant functionality is only supported in Vault Enterprise:
+
+- `local` `(bool: false)` – Specifies if the audit backend is a local mount  
+  only. Local mounts are not replicated nor (if a secondary) removed by
+  replication.
+
 ### Sample Payload
 
 ```json

website/source/api/system/auth.html.md

@@ -74,6 +74,13 @@ For example, mounting the "foo" auth backend will make it accessible at
 - `type` `(string: <required>)` – Specifies the name of the authentication
   backend type, such as "github" or "token".
 
+Additionally, the following options are allowed in Vault open-source, but 
+relevant functionality is only supported in Vault Enterprise:
+
+- `local` `(bool: false)` – Specifies if the auth backend is a local mount  
+  only. Local mounts are not replicated nor (if a secondary) removed by
+  replication.
+
 ### Sample Payload
 
 ```json

website/source/api/system/mounts.html.md

@@ -84,6 +84,13 @@ This endpoint mounts a new secret backend at the given path.
     disabling backend caching respectively. If set on a specific mount, this
     overrides the global defaults.
 
+Additionally, the following options are allowed in Vault open-source, but 
+relevant functionality is only supported in Vault Enterprise:
+
+- `local` `(bool: false)` – Specifies if the secret backend is a local mount  
+  only. Local mounts are not replicated nor (if a secondary) removed by
+  replication.
+
 ### Sample Payload
 
 ```json