Adding annotations to the dot/svg files

[navdeepgaur]

Hi, many thanks for this superb project.
I feel that people might benefit from having the option to also include proto annotations in generated dot/svg files.
I would like to work on that and contribute back, but I am not a Go programmer and finding it a challenge to unravel where to start inspecting the code to add the same functionality.

Is it possible for you to point me to where the functionality for adding name/datatype of the field lives in the code base, so I can start experimenting?

So much better if a feature like this is already in the works.

Thanks!