Change create-router-dom example link in docs to v6 of the library

The [CRA documentation](https://create-react-app.dev/docs/adding-a-router/) on using `react-router-dom` links to an example that showcases the previous version of the library (v5), which is incompatible with the (regular) npm/yarn install of v6. I suggest changing the link to https://github.com/remix-run/react-router/blob/main/docs/getting-started/tutorial.md.
