protocol-capabilities.txt: refer multi_ack_detailed back to pack-protocol.txt
protocol-capabilities.txt: refer multi_ack_detailed back to pack-protocol.txt

pack-protocol.txt explains in detail how multi_ack_detailed works and
what's the difference between no multi_ack, multi_ack and
multi_ack_detailed. No need to repeat here.

Signed-off-by: Nguyễn Thái Ngọc Duy <024f400cd820cb2ddbe54c7fecfd01e45f30bb96@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