README.md in gitdocs-0.5.0.pre7 vs README.md in gitdocs-0.5.0

@@ -57,9 +57,10 @@
 ```
 
 If you have Growl installed on Max OSX, you'll probably want to run:
 
 ```
+brew install caskroom/cask/brew-cask
 brew install growlnotify
 ```
 
 to enable Growl notification support.