Update README.md

[apoorva5ingh]

things i have done

Fixed all YouTube thumbnail links

Standardized headings (all FAQ items use ###)

Added descriptive alt text for all images

Improved formatting and consistency

Added "Quick Start for Contributors" section

Clarified license with CC0 link

Fixed "todo.txt" → "doc/todo.txt"

Improved grammar and readability throughout

Better organized the FAQ answers

Made contributor instructions clearer