Use proper template for initial runnables config contents (#8064)

Release Notes:

- N/A

assets/settings/initial_runnables.json

@@ -2,6 +2,9 @@
 //
 // Example:
 // {
+//     "version": "1",
+//     "runnables": [
+//         {
 //             "label": "human-readable label for UI",
 //             "command": "bash",
 //             // rest of the parameters are optional
@@ -13,7 +16,12 @@
 //             // Whether to use a new terminal tab or reuse the existing one to spawn the process, defaults to `false`.
 //             "use_new_terminal": false,
 //             // Whether to allow multiple instances of the same runnable to be run, or rather wait for the existing ones to finish, defaults to `false`.
-//     "allow_concurrent_runs": false,
-// },
+//             "allow_concurrent_runs": false
+//         }
+//     ]
+// }
 //
-{}
+{
+    "version": "1",
+    "runnables": []
+}