feat(policy): add --admin-policy flag for supplemental admin policies (#20360)

docs/reference/configuration.md

@@ -92,6 +92,13 @@ their corresponding top-level category object in your `settings.json` file.
   - **Default:** `[]`
   - **Requires restart:** Yes
 
+#### `adminPolicyPaths`
+
+- **`adminPolicyPaths`** (array):
+  - **Description:** Additional admin policy files or directories to load.
+  - **Default:** `[]`
+  - **Requires restart:** Yes
+
 #### `general`
 
 - **`general.preferredEditor`** (string):