INSTALLATION.md in trackler-2.1.0.15

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 ## Install the R runtime
 Visit the [CRAN homepage](https://cran.r-project.org/). There you will find download links for Linux, Mac OSX, and Windows. Download and run the installer for your operating system.
 
-If you are using Windows, you may also need to install the [Rtools](https://cran.r-project.org/bin/windows/Rtools/) suite, as some packages may depend on it. Mac users may need to install XCode (particularly its command-line tools) for the same reason.
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 ## Install the RStudio IDE
 RStudio is a popular cross-platform integrated development environment (IDE) for programming in R (and also supports other languages like Python, JavaScript, and Markdown). Using RStudio will make writing your code solutions and running tests easier.
 
 Download and install the [current stable version of RStudio](https://www.rstudio.com/products/rstudio/download/). Or, alternatively, get the [preview version](https://www.rstudio.com/products/rstudio/download/preview/) of an upcoming release.
 
 ## Install the R packages for running tests
-The test runner for the specs is the [`testthat`](https://github.com/hadley/testthat) library from Hadley Wickham, which is a popular choice for R library authors. We also download the [`devtools`](https://github.com/hadley/devtools) library, which is necessary for some parts of the workflow.
+The test runner for the specs is the [`testthat`](https://github.com/hadley/testthat) library from Hadley Wickham, which is a popular choice for R package authors.
 
-To install these libraries, type the following in your RStudio console (or wherever you are using R).
+To install this library, type the following in your RStudio console (or wherever you are using R).
 
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 ```{R}
 install.packages("testthat")
-install.packages("devtools")
 ```
 
 While it is unlikely that you will _need_ to install packages to solve the exercism problems, you may want to bring in a general-purpose utility packages like [`magrittr`](https://github.com/smbache/magrittr) that suit your programming style. To install and load a package like `magrittr`:
 
 ```{R}