Refine message (#13732)

Author: koppor

.github/workflows/on-issue-comment.yml

@@ -33,9 +33,10 @@ jobs:
 
             Happy coding! 🚀
           assignment_suggestion_comment: >
-            👋 Hey @{{ handle }}, looks like you’re eager to work on this issue—great! 🎉
-            It also looks like you skipped reading our [CONTRIBUTING.md](https://github.com/JabRef/jabref/blob/main/CONTRIBUTING.md), which explains exactly how to participate. No worries, it happens to the best of us.
-            Give it a read, and you’ll discover the ancient wisdom of assigning issues to yourself. Trust me, it’s worth it. 🚀
+            👋 Hey @{{ handle }}, looks like you’re eager to work on this issue — great! 🎉
+            It also looks like you don't know how to assign issues to yourself.
+            Please read our [CONTRIBUTING.md](https://github.com/JabRef/jabref/blob/main/CONTRIBUTING.md) to find out how.
+            It will also guide you in other aspects of contributing to JabRef.
       - name: Move issue corresponding column in "Candidates for University Projects"
         uses: m7kvqbe1/github-action-move-issues@main
         if: ${{ steps.assign.outputs.assigned == 'yes' || steps.assign.outputs.unassigned == 'yes' }}