FAQ, working with LLM endpoints and explaining why config-list is a list (#1451)

* FAQ and notebook extended

* Update notebook/oai_openai_utils.ipynb

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

* Update website/docs/FAQ.md

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

* Update website/docs/FAQ.md

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

* Update website/docs/FAQ.md

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

* Update website/docs/FAQ.md

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

* Update FAQ.md

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Co-authored-by: Chi Wang <wang.chi@microsoft.com>