Documentation: Fix duplicate rows in metric-details table

[elray1]

Noting that there are some duplicate rows in the table on this page: https://epiforecasts.io/scoringutils/articles/metric-details.html

[nikosbosse]

Thanks a lot for pointing this out! Will fix this as part of our major overhaul.

[seabbs]

Thanks for reporting!

We should hotfix this in main Vs leaving it unpatched.

[nikosbosse]

Fixed on main and will be pushed to CRAN in the next few days. Thanks again!