README.md in twilio-ruby-5.0.0.rc20 vs README.md in twilio-ruby-5.0.0.rc21

- old
+ new

@@ -9,16 +9,16 @@
 ## Installation
 
 To install using [Bundler][bundler] grab the latest stable version:
 
 ```ruby
-gem 'twilio-ruby', '~> 5.0.0.rc20'
+gem 'twilio-ruby', '~> 5.0.0.rc21'
 ```
 
 To manually install `twilio-ruby` via [Rubygems][rubygems] simply gem install:
 
 ```bash
-gem install twilio-ruby -v 5.0.0.rc20
+gem install twilio-ruby -v 5.0.0.rc21
 ```
 
 To build and install the development branch yourself from the latest source:
 
 ```bash