Opengraph: Enhance support and provide examples in five-page/Bunait

[adrinux]

I have added Hugo's default Opengraph template but we can add further support.

• Auto generate cover/feature images.
• Provide example cover/feature images for blog posts and other content
• Add Opengraph params to front matter archetypes/templates

Useful Opengraph links:

• Hugo docs
• Hugo image overlay function
• aarol.dev
• runtimerror.dev
• hackification.io, includes links to testing tools
• makewithhugo.com