* Add aria-autocomplete='list' in Textaria
ref: https://www.w3.org/TR/wai-aria-1.1/#aria-autocomplete
* Make detect empty string brefore assign upload description
* Change code elements in keyboard-shortcuts component to kbd
* Add Keyboard Shortcuts Legend
Adds a "Keyboard Shortcuts" legend (displayed in the rightmost column)
which is toggled via a new "?" hotkey. When subsequently pressed from
the Keyboard Shortcuts legend, "?" will navigate back to the previous
location.
* Add hidden table headings.
Makes the headings available for accessibility but hides them visually.
