Title markup should distinguish title from navigation about rocket HOT 1 CLOSED

As we are now using @rocket/engine this is supported.

You can write your h1 in any way you want and then define a separate navigation "title".

In markdown it looks like this

```js server
export const menuLinkText = 'Hello';
```

# Hello World

in html it's

<script type="module" server>
export const menuLinkText = 'Hello';
</script>

<h1>Hello World</h1>

in js it's this

export const menuLinkText = 'Hello';

export default () => html`
  <h1>Hello World</h1>
`;

from rocket.