README.md in material-sass-4.0.0.beta vs README.md in material-sass-4.0.0.beta2

@@ -20,11 +20,11 @@
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
-gem 'bootstrap'
-gem 'material-sass'
+gem 'bootstrap',     '~> 4.0.0.beta'
+gem 'material-sass', '~> 4.0.0.beta'
 ```
 And then run the bundler and restart your server to make the files available through the pipeline:
 
 ```console
 $ bundle install