Upgrade mermaid.js to 1.9.0 and add fontawesome css options
Proposal
An upgrade mermaid.js to 1.9.0 in order to support new diagram types and features would improve the documentation and technical writing aspects of the markdown files in Gitlab. This will support XYCharts and Block Diagram's. It will also allow for things such as parallel commits in the git style diagram.
It would also be good to enable using fontawesome icons] which would allow for icons to to be easily included in the diagram.