fix fdo#80490 - string 'Auto Spell Checking'

This only changes the tooltip when you hover over the icon of the
toolbar icon.

Change-Id: I1724fbc6e88f6ed8fe200bd1a1c0b7ac4ff16166
Reviewed-on: https://gerrit.libreoffice.org/9885
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>