Merge pull request #167 from hoytpr/hoyt-setup

Adding How to add R packages

setup.md

@@ -178,7 +178,12 @@ you must install the software described below.
     We use [knitr][cran-knitr], [stringr][cran-stringr], and [checkpoint][cran-checkpoint]
     to format lessons written in R Markdown,
     so you will need to install these to build R lessons
-    (and this example lesson).
+    (and this example lesson). The best way to install these packages is to open an R window and type:
+    ```
+    > install.packages('knitr', dependencies = TRUE)
+    > install.packages('stringer', dependencies = TRUE)
+    > install.packages('checkpoint', dependencies = TRUE)
+    ```
 
 If you want to run `bin/lesson_check.py` (which is invoked by `make lesson-check`)
 you will need Jekyll (so that you have its Markdown parser, which is called Kramdown)