Add an experimental setting for extension config (#16506)

docs/get-started/configuration.md

@@ -830,6 +830,11 @@ their corresponding top-level category object in your `settings.json` file.
   - **Default:** `true`
   - **Requires restart:** Yes
 
+- **`experimental.extensionConfig`** (boolean):
+  - **Description:** Enable requesting and fetching of extension settings.
+  - **Default:** `false`
+  - **Requires restart:** Yes
+
 - **`experimental.extensionReloading`** (boolean):
   - **Description:** Enables extension loading/unloading within the CLI session.
   - **Default:** `false`