README and notebook output update

What's included

• Updated the README with proper Markdown tables for the analysis output sections.
• Added clearer result sections for the first rows preview, fuel type distribution, missing value counts, price summary, average price by body style, and high-horsepower vehicles.
• Executed the notebook so it now contains real generated outputs.
• Fixed notebook execution issues by correcting code-cell formatting and replacing deprecated NumPy usage.

Verification

• Dataset shape verified as 205 rows x 26 columns.
• Notebook executed successfully with 21 code cells and 10 cells containing outputs.
• GitHub detects the project language as Jupyter Notebook.