Update Markdown parser to be on-par with Azure Wiki Markdown

[ricardoboss]

According to this page in the Microsoft docs, the syntax for embedding snippets (like videos or mermaid diagrams) and adding a TOC is a bit different than we currently use: https://learn.microsoft.com/en-us/azure/devops/project/wiki/wiki-markdown-guidance?view=azure-devops-2019

This raises two issues:

• [ ] #55
• [ ] #56

[ricardoboss]

This would also prepare features for use by #9

[ricardoboss]

Closing this in favour of the more general https://github.com/trenz-gmbh/trenz-docs/issues/63