README.md in twilio-ruby-3.16.1 vs README.md in twilio-ruby-4.0.0

@@ -9,10 +9,10 @@
 ## Installation
 
 To install using [Bundler][bundler] grab the latest stable version:
 
 ```ruby
-gem 'twilio-ruby', '~> 3.12'
+gem 'twilio-ruby', '~> 4.0.0'
 ```
 
 To manually install `twilio-ruby` via [Rubygems][rubygems] simply gem install:
 
 ```bash