Notebook improvements: 01_data_exploration.ipynb

1. Try to plot the histogram of model data at the surface level (height level index 1) - change index to 1 and correct spelling of height
2. Generally - avoid italics - not good for people with dyslexia
3. Generally - more space between blocks of code
4. Generally - more comments in code - to explain code
5. Confusion matrices instead/ of pie charts
6. Pretty print long numbers with commas
7. This video might help explain rotors if people aren't sure what they are: https://www.youtube.com/watch?v=jgSZG9SqN_s
8.

Open 01_data_exploration.ipynb and review its code and markdown cells against each requested improvement. Run the notebook to inspect the histogram, charts, formatting, spacing, comments, and number display, then verify that the requested accessibility and explanatory content changes are consistently applied.

Written by the indexing model from the issue text.