Add note to starting symbol

[steinybot]

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Description

It would be nice to have an option to display a note on the starting symbol.

This would make it easy to see the starting point of the diagram which is meaningful if the diagram was generated with the --max-level option set.

Potential Solution

Additional Information

Notes: https://plantuml.com/class-diagram#c909b0b5f0434a64

A related feature would be to add a note to the diagram that contains the options used to generate the diagram.