support PlantUML Rendering

[wuhuizuo]

No description provided.

[sytsereitsma]

@ehuss I'd like to pick this one up if that's ok.

[ehuss]

@sytsereitsma I think it is intended that things like this should be developed as 3rd party preprocessors. Feel free to go ahead and build one, and if you publish it on crates.io we can link to it here and the readme.

[donbowman]

https://github.com/donbowman/gitbook-plugin-local-plantuml is how I did it w/ gitbook.

it would be super nice if we could do a plugin that would be the same syntax as gitlab+plantuml, then the committed files would render while in git as well as being generable.

[leesei]

May be a preprecessor is better for this, see example mermaid integration.

[sytsereitsma]

I created a preprocessor mdbook-plantuml.