docs(linux): say table pages use OFFSET and what the a11y audit covers

[datlechin]

• Release criterion 4: table pages use OFFSET. paging_mode picks keyset or ctid-window walks, but BrowsePager only sends First or Offset, so keyset_walk writes ORDER BY key OFFSET n. Seek paging moves to Still needed.
• Release criterion 8 and the Tests row: the accessibility audit covers the picker, the connect pages, the workspace, the connect dialog and preferences, not every page and dialog. Still needed lists the keyboard sort and resize, named filter fields and cell editors, focus on hide and announced results.
• Corrects docs(linux): correct the roadmap and state each release criterion #3460.