[bazel.build] Problem with /versions

### Page link:

https://bazel.build/versions

### Problem description (include actual vs expected text, if applicable):

Clicking on the version numbers results in 404 error, rather than pointing to

https://bazel.build/versions/

URLS are pointing to

https://bazel.build/versions//versions

Causing 404 error

### Where do you see this issue? (include link to specific section of the page, if applicable)

https://bazel.build/versions

### Any other information you'd like to share?

_No response_

Start at https://bazel.build/versions and inspect how its version links are generated; compare the current links with the expected /versions/ targets. Done when clicking each version reaches the corresponding version page instead of a 404.

Written by the indexing model from the issue text.