[DL]String additions to 'gitg.master'

This is an automatic notification from status generation scripts on:
https://l10n.gnome.org.

There have been following string additions to module 'gitg.master':

+ "Check in vala documentation for datetime to write your own format."
    + "Custom datetime format."
    + "Custom:"
    + "Datetime format"
    + "Predefined:"
    + "Prefered Datatime format of the user."
    + "The datetime format to be used in commit-diff."
    + "Type of datetime format selected."

Note that this doesn't directly indicate a string freeze break, but it
might be worth investigating.
https://gitlab.gnome.org/GNOME/gitg/commits/master