fix install params to install suggests as well

setup.md

 Then, you can install the `js4shiny` package with the following code. If you run into any issues, don't worry: we can diagnose them together at the workshop.
 
 ```r
-devtools::install_git("https://git.garrickadenbuie.com/js4shiny/js4shiny.git")
+devtools::install_git(
+  url = "https://git.garrickadenbuie.com/js4shiny/js4shiny.git", 
+  dependencies = TRUE
+)
 ```
 
 ### Node and npm