Update README.md

[ci skip]

Author: jgabry

README.md

@@ -42,12 +42,15 @@ install.packages("bayesplot")
 * Install latest development version from GitHub (requires [devtools](https://github.com/hadley/devtools) package):
 
 ```r
-if (!require("devtools"))
+if (!require("devtools")) {
   install.packages("devtools")
-
+}
 devtools::install_github("stan-dev/bayesplot", dependencies = TRUE, build_vignettes = TRUE)
 ```
 
+You can also set `build_vignettes=FALSE` for a faster installation from GitHub (the vignettes 
+can always be accessed online anytime at [mc-stan.org/bayesplot/articles](http://mc-stan.org/bayesplot/articles/)).
+
 If you are not using the [RStudio IDE](https://www.rstudio.com/) and you get an
 error related to "pandoc" you will either need to remove the argument
 `build_vignettes=TRUE` (to avoid building the vignettes) or install