Fix missing tags in dataset cards
Fix missing tags in dataset cards:
- aeslc
- empathetic_dialogues
- event2Mind
- gap
- iwslt2017
- newsgroup
- qa4mre
- scicite

This PR partially fixes the missing tags in dataset cards. Subsequent PRs will follow to complete this task.

Related to:
- #4833
- #4891
- #4896
- #4908
- #4921
- #4931
- #4979