The link target in the BDD documentation could be changed because the Cucumber-expression documentation site location was changed to Github.
Line in question docs/bdd.md#L411
The new location is https://github.com/cucumber/cucumber-expressions#readme.
If you visit https://docs.cucumber.io/cucumber/cucumber-expressions/ then you have to click on a link to get to the new location.