sub-diagrams docs

[grivo]

there is no explicit documentation on sub-diagrams, no explanation on nesting limitations, styling of nested diagrams, etc

[The-Lum]

Hi @grivo,

You are right; even if I started (on 2022) a beginning here:

• http://alphadoc.plantuml.com/doc/markdown/en/sub-diagram

Regards, Th.

[grivo]

should something be done here then?

[arnaudroques]

You are right; even if I started (on 2022) a beginning here:

Sorry for the delay... It's online now https://plantuml.com/sub-diagram

Many thanks for your contributions! Anyone can improve this doc now :-)

[grivo]

thanks!