The gitignore(5) manpage already documents $XDG_CONFIG_HOME/git/ignore
but it is easy to forget that it exists. Add a reminder to the
synopsis.
Noticed while looking for a place to put a list of scratch filenames
in the cwd used by one's editor of choice.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>