#4 html book created

For the book to work, I had to:

-change image location to internet location of the image (i.e. the html book will show figures only if people have internet connection)

• change the headings structure (chapters became subchapters and so on)
• write a bookdown.yml file to set where to find the .md files
• run bookdown::render_book("index.Rmd", "bookdown::gitbook")

We can get other forms of books by the way

I did not check all links, it works if it is in the same .md file, but one would need to use another way for referencing to a different file (\@ref())

needs more work to be publishable, do not merge

had to put the repository open, so that figures can be accessed from the book website. Now it works.

Let's discuss this before you make new changes please. I got it to work (apart from links to .md files, that do not work in the book).