Update entity-alias.mdx

it was not clear for approle what the name should be the approle name or the role_id.

Author: jzck

website/content/api-docs/secret/identity/entity-alias.mdx

@@ -19,7 +19,8 @@ This endpoint creates a new alias for an entity.
 - `name` `(string: <required>)` - Name of the alias. Name should be the identifier
   of the client in the authentication source. For example, if the alias belongs
   to userpass backend, the name should be a valid username within userpass
-  backend. If alias belongs to GitHub, it should be the GitHub username.
+  backend. If alias belongs to GitHub, it should be the GitHub username. If alias 
+  belongs to an approle backend, the name should be a valid role_id.
 
 - `id` `(string: <optional>)` - ID of the entity alias. If set, updates the
   corresponding entity alias.