In the abbreviated SvelteKit SSR instructions, `createBrowserClient` is
used in hybrid code that runs on both the server and client, with
changes in the configuration depending on where it's run. That's just
confusing, because the name implies it should not run on the server.
Change it to match the full SvelteKit SSR tutorial, which selectively
runs `createBrowserClient` or `createServerClient` depending on the
current environment.