Include command in output

[GammaGames]

Is your feature request related to a problem? Please describe.
I use pigar with referenced comments to manage my dependencies. It would be useful to include the command used to generate the file underneath the Automatically generated header

Describe the solution you'd like
Add an option to include the run command in the header:

# Automatically generated by https://github.com/damnever/pigar.
# pigar generate --with-referenced-comments

Describe alternatives you've considered
Adding it myself, which is what I do now

Additional context
It should probably be an option, maybe --with-executed-command

[damnever]

I think this is a reasonable idea.