docs: /ping endpoint

[sshilko]

Administration UI also supports /ping endpoint, as well as all others (nsqd, nsqlookupd), it is not mentioned in documentation but usefull.

Dockerfile could be updated maybe too

nsqlookupd:
    image: nsqio/nsq
    command: /nsqlookupd
    healthcheck:
      test: ["CMD-SHELL", "/usr/bin/wget -q -s http://0.0.0.0:4161/ping && exit 0 || exit 1"]

nsqd:
    image: nsqio/nsq
    stop_signal: SIGTERM
    healthcheck:
      test: ["CMD-SHELL", "/usr/bin/wget -q -s http://0.0.0.0:4151/ping && exit 0 || exit 1"]

nsqadmin:
    image: nsqio/nsq
    command: /nsqadmin --lookupd-http-address=nsqlookupd:4161
    healthcheck:
      test: ["CMD-SHELL", "/usr/bin/wget -q -s http://0.0.0.0:4171/ping && exit 0 || exit 1"]

[mreiferson]

opened an issue on https://github.com/nsqio/nsqio.github.io