[L10N] Kickoff of translation for Git 2.15.0 round 1

[Jiang Xin]

Hi,

Git v2.15.0-rc0 has been released, and it's time to start new round of git l10n.
This time there are 68 updated messages need to be translated since last
update.

You can get it from the usual place:

    https://github.com/git-l10n/git-po/

As how to update your XX.po and help to translate Git, please see
"Updating a XX.po file" and other sections in “po/README" file.

--
Jiang Xin