SEO 2024 - corrects unfortunate edit that made statement incorrect

[dwsmart]

Found this:

a sensible approach would be to return a `robots.txt` file with appropriate rules or, if one wishes to restrict crawling, return a [`404 status code`](https://developer.mozilla.org/docs/Web/HTTP/Status/404) for the URL.

Sadly that's the wrong way around, a 404 would mean no restriction, so have edited in this PR to:

a sensible approach would be to return a `robots.txt` file with appropriate rules or, if one does not wish to restrict crawling, return a [`404 status code`](https://developer.mozilla.org/docs/Web/HTTP/Status/404) for the URL.

Sorry I didn't notice earlier!