blame: add support for --[no-]progress option

Teach the command to show progress output when it takes long time to
produce the first line of output; this option cannot be used with
"--incremental" or "--porcelain" options.

git-annotate inherits the option as well.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Edmundo Carmona Antoranz <eantoranz@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-blame.txt b/Documentation/git-blame.txt
index e6e947c..ba54175 100644
--- a/Documentation/git-blame.txt
+++ b/Documentation/git-blame.txt
@@ -10,7 +10,8 @@
 [verse]
 'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
 	    [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
-	    [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>] [--] <file>
+	    [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>]
+	    [--] <file>
 
 DESCRIPTION
 -----------