bookdown::pdf_book:
  includes:
    in_header: preamble.tex
  latex_engine: xelatex
  citation_package: natbib
  keep_tex: yes
bookdown::epub_book: default
bookdown::gitbook:
  css: style.css
  config:
    toc:
      after: |
        <li><a href="https://github.com/TGuillerme/Inapp/" target="blank">Project GitHub page</a></li>
    edit: https://github.com/TGuillerme/Inapp/inst/gitbook/edit/master/%s