Improve onboarding by adding explanations

[afontcu]

• Bumped DOM Testing Library, so now we can demo the new capabilities of *byRole queries (Add semantic HTML elements implicit role support to queryByRole/getByRole selectors dom-testing-library#262).
• Renamed tests to express feature under testing, instead of component details. When I started working with VTL, I had a hard time trying to remember where specific examples were. I feel that expressing the testing intent in the filename will help.
• Added comments to provide a better onboarding experience with the library.
• Removed unused component files.

As usual, feel free to suggest any modification or clarification :)

Thanks!

[afontcu]

Since this is far from any breaking change, I'm gonna merge it, and feel free to suggest any additional modification later :)