Submit an issue with your contribution.
All contributions will be listed in the book. It will take around 1 / 2 days to be listed on my blog and on Dev.to. It will take much longer to be listed in the physical book. Adding more content to the book stretches the cover and I have to use a new ISBN for every new edition I publish. Which is $$$ :(
I'll personally message you when the physical edition is updated.
I don't reccomend forking and submitting a pull request, because I need to add your contribution to the master file. I have a word document that spawns the PDF / HTML of it all.
I might also edit your contribution. For example, someone contributed the shotgun approach to applying to jobs. Don't apply to 1 or 2 companies, apply to 100 companies. This was the opposite of what was in my book, so I couldn't add their contribution as it would be confusing. One moment the author says do X, the next moment the author says "no, X sucks do Y instead".