Easier hiding of first title

Following up on https://github.com/axodotdev/oranda/issues/323, I don't love the oranda-hide class solution (breaks the readme's HTML structure, adds noise to the README.md which people might read in their editors). This can be done via custom CSS instead, but I think even better solution would be a config in `oranda.json`, since it's such a common problem.

CSS solution:
```css
main > h1:first-of-type {
display: none;
}
```

Start by reviewing how oranda.json configuration reaches the generated page, then compare it with the current oranda-hide approach and the CSS selector in the issue. Check issue 323 for prior context. Done means users can configure the first title to be hidden without adding oranda-hide markup to README.md.

Written by the indexing model from the issue text.