Nomad Docs: Fix default vault engine version in nomad secrets block (#1411)

Fix default vault engine version in nomad secrets block

Author: aimeeu

content/nomad/v1.11.x/content/docs/job-specification/secret.mdx

@@ -79,8 +79,8 @@ as an example, you would reference the value in the secret key "foo"  as
 
   Config parameters:
 
-    - `engine` `(string: "kv_v2")` - Specifies what Vault storage engine to
-  query. Options are `kv_v1` and `kv_v2`.
+    - `engine` `(string: "kv")` - Specifies what Vault storage engine to
+  query. Options are `kv` and `kv_v2`.
 
 
 ## Custom providers