[Doc] explaining romanian postprocessing for MBART BLEU hacking
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5943?src=pr&el=h1) Report
> Merging [#5943](https://codecov.io/gh/huggingface/transformers/pull/5943?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/ccbf74a685ae24bd1a0ba1325e4e9a9d62bbb2fa&el=desc) will **decrease** coverage by `0.00%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5943/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5943?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #5943      +/-   ##
==========================================
- Coverage   77.31%   77.31%   -0.01%     
==========================================
  Files         146      146              
  Lines       26214    26214              
==========================================
- Hits        20268    20267       -1     
- Misses       5946     5947       +1     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/5943?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/file\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5943/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9maWxlX3V0aWxzLnB5) | `81.19% <0.00%> (-0.30%)` | :arrow_down: |

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<|||||>@sshleifer just a quick comment on this, from here: https://github.com/pytorch/fairseq/issues/1758#issuecomment-625214318

for EN to RO, there is no point of maximising BLEU by removing diacritics when in real world (WMT human evaluation + SMT Matrix) it is clearly compared with a reference which HAS diacritics. But lot of papers do not do the things right.<|||||>That makes sense @vince62s! This is mostly so I can have a link to paste into a github issue when people ask me why their BLEU score is 27 :) 
