Accessibility improvements

[2LoS]

This is just a little part of the overall work, but I'd like to receive a feedback before continuing. I'd also like to know which level of Accessibility the website should at least support, since, in some situations, this may also have an impact on the design. My idea is to keep the WCAG 2.2, Level AA. This should be a good trade-off between simplicity for development and a better UX for people with disabilities. Moreover, this should make the website conformant with the EAA (EN 301 549).

The header-cta links had "aria-label" attributes that essentially repeated what the information that can be retrieved by the text node. Also, the first link had a mismatch between what there was in the aria-label attribute ("Documentation") and what there's in the text node ("Get Started").

The menu-bar unordered list heavily uses the role attribute. However, this doesn't seem necessary, since the semantics is already provided by the DOM. If the intention was to remove the semantics of <li> to replace it with <a>, I think the issue is more related to this article.

The role="navigation" attribute was used in a <nav> tag, even if this is already provided by the tag itself. Indeed, the <nav> tag has implicitly the navigation role. If the intention was to keep it for compatibility with browsers that doesn't support HTML5, it should be at least applied consistently.

About the star section, there's already a text node, which says "Give us a Star on GitHub", and therefore the use of an aria-label attribute that essentially reports the same isn't useful.

Finally, the SVG code in the logo.hbs file wasn't hidden with the aria-hidden attribute.

[cppalliance-bot]

An automated preview of the documentation is available at https://978.mrdocs.prtest2.cppalliance.org/index.html

[alandefreitas]

I'm not qualified to evaluate the impact of this PR (so I'm inviting Julio to review it), but my impression is that it can't hurt.

[rbbeeston]

I don't see any issues here, all good stuff!

[julioest]

LGTM!