ls-remote: fix synopsis
ls-remote: fix synopsis

git ls-remote takes an optional get-url argument, and specifying the
repository is optional.  Fix the synopsis in the documentation to
reflect this.

Signed-off-by: Thomas Gummerer <b5d5468c18b856edee6cf44fd3ea820cd261b068@gmail.com>
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