ticdc: update open protocol (#4355)
ticdc: update open protocol (#4355)

* update open protocol

* Update ticdc/ticdc-open-protocol.md

Co-authored-by: amyangfei <80fdee9bda15f148894e4274aeb9f01d8f799655@gmail.com>

* Update ticdc/ticdc-open-protocol.md

Co-authored-by: amyangfei <80fdee9bda15f148894e4274aeb9f01d8f799655@gmail.com>
Co-authored-by: TomShawn <3d0966147538bc5ab020e8dffa2c0b746f9728a6@users.noreply.github.com>
pingcap/docs-cn,pingcap/docs-cn