Written by Matt Mullenweg, the co-founder of WordPress, Hello Dolly is included with all WordPress installations as a demonstration of how to write a simple plugin. However, 15 years later, it's no longer demonstrating the best practices that are now in use.
Hello Dolly Redux is a fork of Hello Dolly, with improvements across the board to both code and documentation quality. What's NOT happening is any change to the resulting output - Hello Dolly Redux will display lyrics in the dashboard in exactly the same way as the original plugin.
If you have any further suggestions for quality improvements, please let me know. Or just add your own Pull Request.