Add guide (or modify existing guides or demos) to show how to set default values on components

[freddyaboulton]

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Is your feature request related to a problem? Please describe.
As a gradio user, I wish the guides were clearer on how to set default values on components. This is documented on the docs page but some users may not now to look there.

From the discord:

Describe the solution you'd like
Modify existing guides and or demos (or write a new guide) on how to set default values for components.

Additional context
Add any other context or screenshots about the feature request here.