Adding Turkic X-WMT evaluation set for machine translation
hi! Thank you for all the comments! I believe I addressed them all. Let me know if there is anything else Hi there! I was wondering if there is anything else to change before this can be merged @lhoestq Hi! Just a gentle reminder about the steps to merge this one!  Thanks for the heads up ! I think I fixed the last issue with the YAML tags The CI failure is unrelated to this PR and fixed on master, let's merge :)

Thanks a lot !
This dataset is a human-translated evaluation set for MT crowdsourced and provided by the [Turkic Interlingua ](turkic-interlingua.org) community. It contains eval sets for 8 Turkic languages covering 88 language directions. Languages being covered are:

Azerbaijani (az)
Bashkir (ba)
English (en)
Karakalpak (kaa)
Kazakh (kk)
Kirghiz (ky)
Russian (ru)
Turkish (tr)
Sakha (sah)
Uzbek (uz)

More info about the corpus is here: [https://github.com/turkic-interlingua/til-mt/tree/master/xwmt](https://github.com/turkic-interlingua/til-mt/tree/master/xwmt)

A paper describing the test set is here: [https://arxiv.org/abs/2109.04593](https://arxiv.org/abs/2109.04593)
