This requires the
php.inito be enabled.
You can specify remote Markdown and
bookdown.json config files as
"content" elements. This means you can collect pages and sections from various sources, where those pages and sections are maintained by their respective authors, and combine them into a single book.
For an example of adding remote content, try setting the following
"content": [ "https://raw.githubusercontent.com/pmjones/bookdown-demo/master/libraries/_bookdown.json" ]
Then generate the book. You will see that Bookdown retrieves the remote content and generates it into local HTML files.