docs: add preload script testing tutorial (#2812)

Author: rohan-chidurala

docs/content/docs/developers/troubleshooting.mdx

@@ -33,4 +33,14 @@ You may have to delete cookies to clear the authentication state.
 If you encounter issues such as "Column not found" error, your database may be out of sync with the schema. There are 2 things to try to get it back in sync:
 
 1. Run `bun db:push` to push the schema to the database. If there are conflicts, you can try step 2.
-2. Run `bun db:reset` to fully reset the database and re-run the migrations. WARNING: This will delete all data in the database.
+2. Run `bun db:reset` to fully reset the database and re-run the migrations. WARNING: This will delete all data in the database.
+
+### Testing the Preload Script
+
+If you want to update the preload script and test it with Onlook, follow these steps:
+
+1. Run bun `bun run dev` from the root of the project.
+2. Copy the file `apps/web/client/public/onlook-preload-script.js` into to `public/onlook-preload-script.js` in the code tab in onlook or the codesandbox interface.
+3. Refresh the localhost tab. You should now be able to test the preload script.
+
+If you want to update the preload script and test any changes, you need to refresh the localhost tab.