Added a note about issue with installing packages by means of R Markdown / knitr.

Author: ASonCourse

PA1_template.Rmd

@@ -49,6 +49,11 @@ if (!require(dplyr)) install.packages("dplyr")
 library(dplyr)
 ```
 
+NOTE:
+
+Installing packages by means of R Markdown (`knitr` document) is not advised. The consensus seems to be that users should manage their own package library. We should assume that people know how to install a missing package. Here we've opted to download and install the package _only_ if it's necessary. Arguably a number of users might have dplyr installed / loaded already. See this [resource](https://stackoverflow.com/questions/33969024/install-packages-fails-in-knitr-document-trying-to-use-cran-without-setting-a) for more on the subject.
+
+
 Calculate mean total number of steps per day:
 
 ```{r mean_total_steps}