[PATCH] format-patch: Update the `-3` example

In the EXAMPLES section, `git-format-patch -3` doesn't work
anymore. Update it to read `git format-patch HEAD~3`. The example was
introduced in 7c49628 and had not been updated since.

Signed-off-by: Ramkumar Ramachandra <redacted>
---
 Documentation/git-format-patch.txt |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index 4b3f5ba..2a44472 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt

@@ -271,7 +271,7 @@ use it only when you know the recipient uses git to apply your patch.
 as e-mailable patches:
 +
 ------------
-$ git format-patch -3
+$ git format-patch HEAD~3
 ------------
 
 SEE ALSO

-- 
1.7.2.2.409.gdbb11.dirty