Update meta description
Update meta description

This will match [the description field in the content item](https://github.com/alphagov/special-route-publisher/pull/123).

The main reason for this change is to include the word "checker" in the
text, as we've noted that this is commonly used by people searching for
this page.

alphagov/collections,alphagov/collections,alphagov/collections,alphagov/collections