doc: "git checkout -b/-B/--orphan" always takes a branch name
doc: "git checkout -b/-B/--orphan" always takes a branch name

While the synopsis section makes it clear that the new branch name
is the parameter to these flags, the option description did not.

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