GitBook links no longer work

[nina-py]

Great book, thank you for writing it!

I've noticed that the GitBook links no longer work - none of the downloadable options work and neither is the link in the "About" section. Can still read everything on here, obviously, but perhaps these can be fixed as I understand GitBook has gone through some major changes recently but is still free for personal projects. Alternatively, there is a free GitBook-inspired option you could move the book to: https://github.com/filipowm/BooGi .