Or just delete the first two lines in the entry above and replace it with
As of this time (2016) the
GRUB_HIDDEN_TIMEOUT_QUIET options have already been depreciated. So don't use them any more. Instead, you can use
info -f grub -n 'Simple configuration'
You have this:
If this option is unset or set to 'menu', then GRUB will display
the menu and then wait for the timeout set by 'GRUB_TIMEOUT' to
expire before booting the default entry. Pressing a key interrupts
If this option is set to 'countdown' or 'hidden', then, before
displaying the menu, GRUB will wait for the timeout set by
'GRUB_TIMEOUT' to expire. If <ESC> is pressed during that time, it
will display the menu and wait for input. If a hotkey associated
with a menu entry is pressed, it will boot the associated menu
entry immediately. If the timeout expires before either of these
happens, it will boot the default entry. In the 'countdown' case,
it will show a one-line indication of the remaining time.