Bring subsite accessibility standards up to the same level as CNCF.io

[cjyabraham]

Audit and improve the accessibility standards of all CNCF subsites to bring them up to WCAG AA 2.1 standards, similar to the main CNCF site. Expand the scope of the current Accessibility Statement to include all CNCF sites.

[seokho-son]

Thanks @cjyabraham This issue is nice! :)

[jihoon-seo]

+1, it would be great to make subsites more accessible!