reshape introduction and welcome episodes

[n400peanuts]

Introduction episode must be reshaped as follows:

• re-add exercise on nlp tech that people can find in their everyday life
• add:

1. introduction of the problems we are going to solve
2. which datasets we are going to use
3. possibly a picture of the technological breakthrough of nlp
4. End emphasising that we are going to cover only: preprocessing, w2v, transformers and LLM and prompt engineering
5. anticipate the structure of the course in 2 days, what we cover in day 1, what we cover in day 2, what at the end the learners will be able to know at the end of the full course