README.md: Refactor home page with new contents and structure

[gmacario]

Closes #

📑 Description

✅ Checks

• [x] My pull request adheres to the code style of this project
• [ ] My code requires changes to the documentation
• [x] I have updated the documentation as required
• [x] All the tests have passed

ℹ Additional Information

[gmacario]

Here some suggestions I found reading the doc:

...

All the rest seems okay to me 😄

OK, so I think that with https://github.com/B-AROL-O/ARNEIS/pull/292/commits/fe921315664d15f1e3eb3cfdf690710c73884e89 everything is ready to be merged