Changed to make more sense to non-tech-savvy users.
See https://material.io/guidelines/style/writing.html for
writing guidelines.

Changed grid default value from string to integer, since the value
is effectively an integer, and no point in being a string.

Change-Id: I6c1737927e7f9d20536756c3cb8b7059cf49500b
Reviewed-on: https://gerrit.libreoffice.org/34074Reviewed-by: Aleksandar Stefanović <theonewithideas@gmail.com>
Tested-by: Aleksandar Stefanović <theonewithideas@gmail.com>