rebase: add --reset-author-date

The previous commit introduced --ignore-date flag to rebase -i, but the
name is rather vague as it does not say whether the author date or the
committer date is ignored. Add an alias to convey the precise purpose.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 79cecd2..1ee3bb4 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -450,6 +450,7 @@
 	date. This option implies `--force-rebase`.
 
 --ignore-date::
+--reset-author-date::
 	Instead of using the author date of the original commit, use
 	the current time as the	author date of the rebased commit.  This
 	option implies `--force-rebase`.