add paragraph on prerequisites

index.Rmd

@@ -21,6 +21,8 @@ knitr::include_graphics('images/cover.jpg', dpi = 150)
 In 2015, we wrote a statistics book on Master/PhD-level Bayesian data analyses in ecology [@KornerNievergelt2015] based on scripts we used for our statistics courses. You can order it [here](https://www.elsevier.com/books/bayesian-data-analysis-in-ecology-using-linear-models-with-r-bugs-and-stan/korner-nievergelt/978-0-12-801370-0). People seemed to like it [e.g. @Harju2016]. Since then, two parallel processes happen. First, we learned more and we became more confident in what we do and what we don't do, and why we do what we do. Second, clever people continuously develop software that broaden the spectrum of ecological models that can be applied by ecologists working with R. Therefore, with this e-book, we substantially revised the text of the printed book, and we add new material.
 
 ## About this book {-}
+As a prerequisite, you should be familiar with the basics of R, such as loading a package and reading in data, you should know how to apply a R function and that you can access a help file for each of them using "?<name of function>", e.g. `?c` for the help file of the function `c()`. If you are a complete novice, you find tutorials online. You should know that code is generally written into a script that is saved, and that code is executed in the console. We use [RStudio](https://posit.co/download/rstudio-desktop/) as an editor to work on our scripts and to execute code.
+
 We understand this e-book as a dynamic project. Based on contributions from readers and based on further developments in R and its packages, we plan to continuously update the text. On the other hand, at any point in time, the published e-book should be coherent and contain all the essential steps needed to perform the analyses covered, such that it can be used for self-study or as a course script.
 
 While we show the R-code behind most of the analyses, we sometimes choose not to show all the code in the html version of the book, e.g. for illustrations. But you can always consult the [public GitHub repository](https://github.com/TobiasRoth/BDAEcology) with the R Markdown files that were used to generate the book.