docs(tutorials): note OpenAI-compatible base_url for chat apps - #1505

Changed pages include:

• index.html - view
• 404.html - view
• deploy.html - view
• develop.html - view
• get-started.html - view
• index/index.html - view
• knowledge-base.html - view
• menu.html - view
• style-guide.html - view
• deploy/concepts.html - view

There are more changes not included in the list