New and Updated Guides for 3.0

[abidlabs]

This is a tracking / brainstorming issues for adding New Guides to the Gradio website, as well as updating older guides to use 3.0 features:

Topics for new guides:

• Embedding gradio spaces as web components (Guide on embedding Gradio demos #703, )
• Contributing custom components (Custom Components in Gradio #1432)
• Multi-step Blocks (e.g. audio to text to sentiment)
• Optional components, input-less components, output-less components (A guide on optional components, input-less components, output-less components, etc. #500)
• Changing visibility
• Using the 3D model component
• Plotly (and other plots!)
• Building simple games with Gradio
• Named-entity recognition
• Real-time webcam
• Developer mode (reloading, blocks magic) (Add reload to docs #1365)
• other ideas...

Updating older guides:

• Use web components instead of iframes in guides
• Generally use 3.x syntax (gradio.components) instead of 2.x syntax (gradio.inputs), etc.
• Check the real-time speech recognition one

[nateraw]

@abidlabs I'll give "Real-time webcam" a try 😄

[abidlabs]

Let's close this issue and use the doc for tracking. Easier to comment / edit / assign to people. I'll move the guides over