Documentation/git-branch: add default for --contains
Documentation/git-branch: add default for --contains

Indicate that the commit parameter of --contains defaults to HEAD.

Signed-off-by: Vincent van Ravesteijn <1c466654e4be28a1d0eae862fbfcbb6a3fd67387@lyx.org>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git