Reorganize [Overview](https://docs.tremor.rs/overview/) with user-centeredness in mind

[Licenser]

This is an extrat from the Docs Assessment done by @celestehorgan

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I suggest creating a new section with the following content:
- The information on The docs index as a page titled "Overview", with subpages:
- Architecture Overview (note: you could break out each of the "Model" sections into their own subpages)
- History, and I would consider titling this "Release log" or something similar
- Understanding Data