All you have to do is click File > Download as > EPUB Publication.
EPUB documents are widely supported across most ebook readers, so this could be a good choice for sharing your work with others.
The format isn’t as well supported on Windows, but is an open-source cross-platform viewer which handles ePubs and many other formats: FB2, MOBI, PDF, more.
Google’s official announcement of the update is here.
This article originally appeared at softwarecrew.co.uk