AI Module Week 5 Topic 2: OpenAI Chat Completions API

Intro and overview of openai api chat completions endpoint. Go over required params (messages/model), but also the important optional params (max_tokens, temperature, top_p etc). Mention responses endpoint (more friendly to tools/agents). Discuss and demonstrate use of moderations endpoint.   `lessons/05_AI_intro/02_open_ai_api.md`