Guided onboarding and/or walkthrough tutorial in docs

[whitep4nth3r]

When you open a new app and see an empty slate — especially when you're just exploring – it's beneficial to have some kind of guided onboarding to help set users up for success.

For example:

1. Create your first app
2. Create your first topic
3. Create your first subscription

And guide users with extra context about the decisions they are making along the way.

Additionally, users should be able to opt out/dismiss this easily.

A good MVP for this would be to have clear and actionable walkthroughs for specific real-world use cases on the docs.