Improve documentation pagination accessibility

Created by: ngyikp

Fixes #22009 (closed):

• Add rel="prev" and rel="next", also good for SEO!
• Remove .sr-only span for previous/next page, there is already aria-label
• Add aria-disabled="true" and aria-current="page"

Also fix the active state on the Sizing section, the current page number was using the disabled look, it should be the active look instead.