Proposal: improve helpful issues for Nuxters contributions

[maximepvrt]

Currently, Nuxters, the contribution scoring tool for Nuxt, lacks a metric to reward users for valuable contributions that lead to issue resolution via merged merge request. I propose adding to the category of "useful issue" the consideration of these issues that have been closed by a merged merge request as useful issues. For instance, issue #19930 was resolved through this merge request: nuxt/nuxt#19930.

Let's enhance Nuxters to acknowledge such contributions and motivate meaningful collaborations.