Update documentation.

[jorgebucaran]

• Rename Picodom to Ultradom.
• Use new VNode shape {nodeName, attributes, children}
• Use h and virtual DOM consistently across the documentation.
• Add missing commas to usage example.

[jorgebucaran]

@lukejacksonn Once you merge this, could also please update your repository's tags — remove ~picodom~ and change it to ultradom. 🙏

[lukejacksonn]

LGTM. Yes can do. Thanks 🎉