Add note about tools in main README

Author: wch

README.md

@@ -50,9 +50,13 @@ If you do not wish to update your code at this time, you can use the [shinyBoots
 If you prefer to install an older version of Shiny, you can do it using the devtools package:
 
 ```R
-devtools::install_version("shiny", version = "0.10.2")
+devtools::install_version("shiny", version = "0.10.2.2")
 ```
 
+## Development notes
+
+The Javascript code in Shiny is minified using tools that run on Node.js. See the tools/ directory for more information.
+
 ## License
 
 The shiny package is licensed under the GPLv3. See these files in the inst directory for additional details: