edited the code for first text generation app - had minor errors

Author: Saibernard

06-text-generation-apps/README.md

@@ -192,7 +192,7 @@ Now that we learned how to set up and configure openai, it's time to build your
  messages = [{"role": "user", "content": prompt}]
 
  # make completion
- completion = client.chat.completions.create(model=deployment, messages=messages)
+ completion = openai.chat.completions.create(model=deployment_name, messages=messages)
 
  # print response
  print(completion.choices[0].message.content)