Update chat_generatetext.cs

Author: achandmsft

docs/quickstart/chat/chat_generatetext.cs

@@ -1,5 +1,5 @@
 // SAMPLE: Generate text from a simple prompt
-// GUIDANCE: https://platform.openai.com/docs/guides/text?api-mode=chat 
+// GUIDANCE: https://platform.openai.com/docs/quickstart?api-mode=chat 
 // HOWTO: Instructions to run this code: https://aka.ms/oai/net/start 
 #:package OpenAI@2.2.*-*
 #:property PublishAot false