Document git blame --reverse.

This was introduced in 85af7929ee but
not documented outside the commit message.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/blame-options.txt

@@ -41,6 +41,13 @@ of lines before or after the line given by <start>.
 -S <revs-file>::
 	Use revs from revs-file instead of calling linkgit:git-rev-list[1].
 
+--reverse::
+	Walk history forward instead of backward. Instead of showing
+	the revision in which a line appeared, this shows the last
+	revision in which a line has existed. This requires a range of
+	revision like START..END where the path to blame exists in
+	START.
+
 -p::
 --porcelain::
 	Show in a format designed for machine consumption.

Documentation/git-blame.txt

@@ -10,7 +10,7 @@ SYNOPSIS
 [verse]
 'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-p] [-w] [--incremental] [-L n,m]
             [-S <revs-file>] [-M] [-C] [-C] [--since=<date>]
-            [<rev> | --contents <file>] [--] <file>
+	    [<rev> | --contents <file> | --reverse <rev>] [--] <file>
 
 DESCRIPTION
 -----------