Add four missing diagrams, provide contributor instructions, and update mermaid.

[jtreher]

• The addon was missing support for MindMaps, Quadrants, XY, and Block-Beta.

  • Added Support for those types.

• Added instructions for contributors to help out.

  • Let me know if you'd like me to change anything. I was a little iffy on the instructions. It's seems like there should be something more general purpose, but a lot of it is all about creating a plugin from scratch.

• Bumped mermaid to the latest version.

Screenshots of new diagrams rendering in my local vanilla Backstage instance:

Mermaid adds Katex support in 10.8

Fixes https://github.com/johanneswuerbach/backstage-plugin-techdocs-addon-mermaid/issues/54

[johanneswuerbach]

@jtreher this looks great, would you mind running yarn install locally and committing the resulting lockfile? This should resolve the CI issue.

[jtreher]

@johanneswuerbach Ah, I was running yarn install, but it was only generating the lock file for the root Backstage folder. I had to remove the monorepo tooling and was able to generate it just for the plugin.

Also, I bumped the package version.

It still seems like I need to do something.

[johanneswuerbach]

Thank you for the contribution @jtreher 🤩 , published as backstage-plugin-techdocs-addon-mermaid@0.13.0.