Document the -n command-line option to git-unpack-objects

This patch documents the -n command-line option to git-unpack-objects,
as it was previously undocumented.

Signed-off-by: Nikolai Weibull <nikolai@bitwi.se>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-unpack-objects.txt

@@ -8,7 +8,7 @@ git-unpack-objects - Unpack objects from a packed archive.
 
 SYNOPSIS
 --------
-'git-unpack-objects' [-q] <pack-file
+'git-unpack-objects' [-n] [-q] <pack-file
 
 
 DESCRIPTION
@@ -19,6 +19,10 @@ one-object" format in $GIT_OBJECT_DIRECTORY.
 
 OPTIONS
 -------
+-n::
+        Only list the objects that would be unpacked, don't actually unpack
+        them.
+
 -q::
 	The command usually shows percentage progress.  This
 	flag suppresses it.

unpack-objects.c

@@ -6,7 +6,7 @@
 #include <sys/time.h>
 
 static int dry_run, quiet;
-static const char unpack_usage[] = "git-unpack-objects [-q] < pack-file";
+static const char unpack_usage[] = "git-unpack-objects [-n] [-q] < pack-file";
 
 /* We always read in 4kB chunks. */
 static unsigned char buffer[4096];