examples/seq2seq supports translation (#5202)

examples/seq2seq/train_distilbart_xsum.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+export PYTHONPATH="../":"${PYTHONPATH}"
+export BS=16
+export GAS=2
+python distillation.py \
+  --learning_rate=3e-4 \
+  --do_train \
+  --do_predict \
+  --fp16 \
+  --val_check_interval 0.1 --n_val 1000 \
+  --teacher facebook/bart-large-xsum --data_dir $XSUM_DIR \
+  --max_target_length=60 --val_max_target_length=60 --test_max_target_length=100 \
+  --student_decoder_layers 6 --student_encoder_layers 12 \
+  --freeze_encoder --freeze_embeds \
+  --model_name_or_path IGNORED \
+  --alpha_hid=3. --length_penalty=0.5 \
+  --train_batch_size=$BS --eval_batch_size=$BS --gradient_accumulation_steps=$GAS --num_train_epochs=6 \
+  --tokenizer_name facebook/bart-large \
+  --output_dir distilbart_xsum_12_6 \
+  $@