Use extended Editor type in useSlateWithV return type (#5763)

* Use extended `Editor` type in `useSlateWithV` return type

So it matches the return types of `useSlate` and `useSlateStatic`. The
`useSlateWithV` return object's `editor` property is currently typed as
just a `ReactEditor`, which causes type errors in our app when we try to
use it as the extended `Editor` type.

* Fix return types in "Editor hooks" docs

packages/slate-react/src/hooks/use-slate.tsx

@@ -34,7 +34,7 @@ export const useSlate = (): Editor => {
   return editor
 }
 
-export const useSlateWithV = () => {
+export const useSlateWithV = (): { editor: Editor; v: number } => {
   const context = useContext(SlateContext)
 
   if (!context) {