config.txt: clarify core.checkStat

The description of this key does not really tell what the 'minimal'
mode checks and does not check.  The description for the 'default'
mode is not much better and just says 'all fields', which is unclear
and is not even correct (e.g. we do not look at 'atime').

Spell out what are and what are not checked under the 'minimal' mode
relative to the 'default' mode to help those who want to decide if
they want to use the 'minimal' mode, also taking information about
this mode from the commit message of c08e4d5b5c (Enable minimal stat
checking - 2013-01-22).

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions