Improved authoring examples with interactive maps

[Malvoz]

Interactive maps are more engaging than images. We can use https://maps4html.org/web-map-doc/dist/mapml-viewer.js as the script source.

The authoring examples section should have a few maps showcasing a basic map and capabilities for common use cases:

1. Basic map: Only uses the required attibutes (zoom, lat, lon) with 1 layer source (src)
2. Customized map: Extends a basic map by specifying controls, width, height, and uses an alternative projection (e.g. CBMTILE)
3. Two-layered map: Extends the Customized map with an inline layer with <feature> & CO describing 1 marker

At a later point we could include more examples, such as:

4. Vector tiles/features
5. CSS styled map content
6. Custom projection
7. Advanced map that uses most/all MapML elements