dillon1000/react

fix link to ReactDOMHostconfig in reconciler docs (#25788)

## Summary

Reference to #25716, changed old link to a new, now page exist, instead
of 404.

## How did you test this change?

yarn test
and by clicking on the link of host config in
https://github.com/facebook/react/blob/main/packages/react-reconciler/README.md#practical-examples