Similar question here
I had this question because I don't understand github pages, the underlying steps involve
build the _book folder, this is the static content that will be served
create gh-pages branch copy the _book folder content into gh-pages
github will then serve the content
the command
gitbook publish
will finish all 3 steps. but I am not familiar withgrunt
as well , asnpm install .
is a pre-step.