Update the README to describe the repository conceptually to visitors

[Zifah]

@ThatBobo

Currently, the README file describes individual files and folders within the repository. However, it is lacking an introduction which tells a visitor what the repository is all about in the first place.

Considering adding an introduction to the repository so a busy user can decide quickly if this is something they would like to engage with further. Sample sections could be:

1. What is HTML6?
2. Quick demo/How to test?
3. How to contribute?

[ThatBobo]

Ok, I will do it, also remember that the since this is for README, the documentation label is needed