[Docs] Explanation: Pick a Router

[brookslybrand]

Describe what's incorrect/missing in the documentation

We need clear guidance on choosing between React Router's different routing approaches: component-based routing (<BrowserRouter>, etc.), data routers (createBrowserRouter, etc.), and framework mode.

You can piece together the information on these different routers in a few places, but it would be good to have a single doc like the v6 doc that simply explains all the options, the differences, and where to go next.