hello-zero main.zig example uses uppercase app method names

[tricarte]

Because of this, example does not compile.

im-ng.github.io/zero-docs/hello-zero.html

    // create zero App
    // internally zero loads container with configured services attached
    const app = try App.New(allocator);

    // register our first route on app
    try app.Get("/json", jsonResponse);

    // start the server by invoking run
    try app.Run();