[Docs]: Using Middleware in Data Mode requires module augmentation

[silvenon]

Describe what's incorrect/missing in the documentation

This is not mentioned in the docs, but in order for context in loaders not to be any, the Future interface in react-router needs to be augmented:

declare module 'react-router' {
  interface Future {
    v8_middleware: true;
  }
}

I don't think there's a way around this, so my proposal is to add this to usage with Data Mode.

[dbergey]

I found that if I type my middleware functions as MiddlewareFunction<RouterContextProvider> it helps

[silvenon]

Unfortunately that doesn't help in my case, RouterContextProvider is already the default value.