feat: add etcd register

[qiuyuyin]

What type of PR is this? register-etcd

What this PR does / why we need it (English/Chinese): Which issue(s) this PR fixes: Todo:

• [x] add example with etcd.
• [x] makefile change to docker.
• [ ] add licenses.
• [x] optimize README.
• [x] add unit test with etcd-register.
• [ ] add more unit test with hertz