because it lists just image formats, not all formats.

"image" is what seems to be the word of the moment for graphics/pictures/etc so
use that

Change-Id: I85c8abd11a121ce000f2850857a967fada11e809
Reviewed-on: https://gerrit.libreoffice.org/73275
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>