add more NMT papers

README.md

@@ -251,16 +251,20 @@ I would continue adding papers to this roadmap.
 
 ## 3.5 Machine Translation
 
-**[92]** Bahdanau, et al. "**Neural Machine Translation by Jointly Learning to Align and Translate**". In arXiv preprint arXiv:1409.0473v7, 2014. [[pdf]](https://arxiv.org/pdf/1409.0473v7.pdf):star::star::star::star:
+> Some milestone papers are listed in RNN / Seq-to-Seq topic. 
 
-**[93]** Lee, et al. "**Fully Character-Level Neural Machine Translation without Explicit Segmentation**". In arXiv preprint arXiv:1610.03017, 2016. [[pdf]](https://arxiv.org/pdf/1610.03017.pdf):star::star::star::star::star:
+**[92]** Luong, Minh-Thang, et al. "**Addressing the rare word problem in neural machine translation**." arXiv preprint arXiv:1410.8206 (2014).[[pdf]](http://arxiv.org/pdf/1410.8206) :star::star::star:star:
 
-**[94]** Wu, Schuster, Chen, Le, et al. "**Google's Neural Machine Translation System: Bridging the Gap between Human and Machine Translation**". In arXiv preprint arXiv:1609.08144v2, 2016. [[pdf]](https://arxiv.org/pdf/1609.08144v2.pdf):star::star::star::star:
 
-**[95]** Sennrich, et al. "**Neural Machine Translation of Rare Words with Subword Units**". In arXiv preprint arXiv:1508.07909, 2015. [[pdf]](https://arxiv.org/pdf/1508.07909.pdf):star::star::star:
+**[93]** Sennrich, et al. "**Neural Machine Translation of Rare Words with Subword Units**". In arXiv preprint arXiv:1508.07909, 2015. [[pdf]](https://arxiv.org/pdf/1508.07909.pdf):star::star::star:
 
-**[96]** Chung, et al. "**A Character-Level Decoder without Explicit Segmentation for Neural Machine Translation**". In arXiv preprint arXiv:1603.06147, 2016. [[pdf]](https://arxiv.org/pdf/1603.06147.pdf):star::star:
+**[94]** Luong, Minh-Thang, Hieu Pham, and Christopher D. Manning. "**Effective approaches to attention-based neural machine translation**." arXiv preprint arXiv:1508.04025 (2015). [[pdf]](http://arxiv.org/pdf/1508.04025) :star::star::star::star:
 
+**[95]** Chung, et al. "**A Character-Level Decoder without Explicit Segmentation for Neural Machine Translation**". In arXiv preprint arXiv:1603.06147, 2016. [[pdf]](https://arxiv.org/pdf/1603.06147.pdf):star::star:
+
+**[96]** Lee, et al. "**Fully Character-Level Neural Machine Translation without Explicit Segmentation**". In arXiv preprint arXiv:1610.03017, 2016. [[pdf]](https://arxiv.org/pdf/1610.03017.pdf):star::star::star::star::star:
+
+**[97]** Wu, Schuster, Chen, Le, et al. "**Google's Neural Machine Translation System: Bridging the Gap between Human and Machine Translation**". In arXiv preprint arXiv:1609.08144v2, 2016. [[pdf]](https://arxiv.org/pdf/1609.08144v2.pdf) **(Milestone)** :star::star::star::star:
 
 
 ## 3.6 Audio