Sitemap instructions fails at parseRoute

Hi!

Tried to follow the SEO guide at the IHP docs: https://ihp.digitallyinduced.com/Guide/seo.html

In `FrontController.hs` is fails with the following error message:

```
• Could not deduce (Controller SitemapController)
arising from a use of ‘parseRoute’
from the context: (?applicationContext::IHP.ApplicationContext.ApplicationContext,
?application::WebApplication, ?context::RequestContext)
bound by the type signature for:
controllers :: forall controller.
(?applicationContext::IHP.ApplicationContext.ApplicationContext,
?application::WebApplication, ?context::RequestContext) =>
[RouteParser]
at /home/lillo/kode/kompak.ai/Web/FrontController.hs:14:5-15
• In the expression: parseRoute @SitemapController
In the expression:
[startPage WelcomeAction, parseRoute @SitemapController,
parseRoute @StaticController, parseRoute @PostsController]
In an equation for ‘controllers’:
controllers
= [startPage WelcomeAction, parseRoute @SitemapController,
parseRoute @StaticController, ....]typecheck(-Wdeferred-type-errors)
```

Start with the SEO guide at https://ihp.digitallyinduced.com/Guide/seo.html and reproduce its sitemap setup in Web/FrontController.hs. Investigate the reported parseRoute @SitemapController type error; done means the documented instructions no longer produce this error or the guide clearly reflects the required setup.

Written by the indexing model from the issue text.