[NLP] Intro

Here, under NLP categories, the historical flow of the overall model / process will be presented.

The timeline is as follows:

1. Recurrent Neural Network (RNN) - Rumelhart, 1986,
2. Long Short-Term Memory (LSTM) - Hochreiter, Schmidhuber - 1997,
3. Sequence to Sequence (Seq2Seq)</u> - Sutskever, Vinyals, Le - 2014,
4. Attention pt. 1 & Attention pt. 2 - Google - 2017
5. GPT 1, 2, 3 - OpenAI - 2018 ~ 2020,
6. Bidirectional Encoder Representations from Transformers - Google - 2018.

Plus, some interesting models are to be reviewed and explained in simpler ways.