Delete: ch1_tables_medical_insurance (1).ipynb, ch2_timeseries_air_quality (1).ipynb, ch3_images_trashnet (1).ipynb, ch4_text_imdb (1).ipynb

Create: ch1_tables.ipynb, ch2_timeseries.ipynb, ch3_images.ipynb, ch4_text.ipynb

Update: README.md

Create: ch1_tables_medical_insurance (1).ipynb, ch2_timeseries_air_quality (1).ipynb, ch3_images_trashnet (1).ipynb, ch4_text_imdb (1).ipynb, requirements.txt