Fix ade_corpus_v2 config names
There are currently some typos in the config names of the `ade_corpus_v2` dataset, I fixed them:

- Ade_corpos_v2_classificaion -> Ade_corpus_v2_classification
- Ade_corpos_v2_drug_ade_relation -> Ade_corpus_v2_drug_ade_relation
- Ade_corpos_v2_drug_dosage_relation -> Ade_corpus_v2_drug_dosage_relation