Fix documentation of fetch-pack that implies that the client can disconnect after sending wants. Specify conditions under which the client can terminate the connection early. Previously, an unintended behavior was possible which could confuse servers. Based-on-patch-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Alex Neronskiy <zakmagnus@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>