[PATCH] Docs gitk: Explicitly mention -d, --date-order option

gitk can show the commits in --date-order which is commits sorted by
Committer Date. -d is a gitk feature, which in turn converts to
--date-order, which is a git-log feature. It is useful to mention.

git-branch, a Javascript based git repo viewer, displays in
--date-order.

Signed-off-by: Clifford Caoile <redacted>
---
 Documentation/gitk.txt |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/Documentation/gitk.txt b/Documentation/gitk.txt
index 29edafc..d247d63 100644
--- a/Documentation/gitk.txt
+++ b/Documentation/gitk.txt

@@ -41,6 +41,12 @@ frequently used options.

 	Show all branches.

+-d, --date-order::
+
+	Shows commits by Committer Date order. Note that the date column is
+	Author Date, so it may appear to be out of order. If this option is
+	not set, gitk displays in --topo-order. See linkgit:git-log[1].
+
 <revs>::

 	Limit the revisions to show. This can be either a single revision

-- 
1.5.4.2.1161.g1a6f0