Is there any documentation for iBooks Author.

Apple has a FAQ article at: support.apple.com/kb/HT5071

You can also go here for information: www.apple.com/support/mac-apps/ibooksauthor/

Google also has a lot of third party information with a simple search.

And of course you can always to to the iBooks Author forum here on Apple Support Communities. The link for that is here: discussions.apple.com/community/ibooks/ibooks_author