[add-resource] New Theme: Quark-A11y

[pmoreno-rodriguez]

I've created a new theme: Quark-A11y. It is a fork of the original theme Quark, focused on improving accessibility while staying as faithful as possible to the original theme. This version introduces improved ARIA labels and more semantic HTML markup to provide a better experience for users relying on assistive technologies.

Additionally, the Spectre.css framework has been updated to version 0.5.9.

Details please see in the repo:

Theme: https://github.com/pmoreno-rodriguez/grav-theme-quark-a11y

Check it out, try it out, and if you have any improvements or suggestions to make, feel free to do so via Issues or Pull Request!