[Docs]: `useBlocker` usage

[flaff]

Describe what's incorrect/missing in the documentation

Hello 👋

Using useBlocker causes "Error: useBlocker must be used within a data router." error, but there is no DataRouter or useBlocker in docs. How should it be used?

[akoskm]

If this error appears inside of a test, make sure you wrap your component with the stub router: https://reactrouter.com/start/framework/testing#testing

[einarq]

Probably have to refer to the v6 docs for this:

• https://reactrouter.com/6.29.0/routers/picking-a-router
• https://reactrouter.com/6.29.0/hooks/use-blocker

[marcellobarile]

On top of that, this table here looks misleading as it has green ticks for all the modes about useBlocker, while (if I got it correctly) that's not true.

[brookslybrand]

Thanks @flaff for raising this!

We do now have a useBlocker doc

@einarq I've added some of the context in those docs that were missing in #13803

@marcellobarile the table seems to be corrected now. Thanks for pointing this out though