Fix ruby virtual_agent casing.

Author: Sarah Stringer

twiml/voice/connect/virtualagent/virtualagent.5.x.rb

@@ -2,7 +2,7 @@
 
 response = Twilio::TwiML::VoiceResponse.new
 response.connect(action: 'https://myactionurl.com/twiml') do |connect|
-    connect.virtualagent(connector_name: 'project', status_callback: 'https://mycallbackurl.com')
+    connect.virtual_agent(connector_name: 'project', status_callback: 'https://mycallbackurl.com')
 end
 
 puts response