change single quotation marks to double quotation marks

[liulei18]

• following instructions order 3 in README.md, I add the following configuration into the orange.conf file

  
  "consul": {
      "host" : "10.0.201.156",
      "port" : 8500,
      "interval" : 10,
      "token" : 'token'
  }

* then i execute ``` orange start```, i get a error log

2019/07/22 18:10:20 [error] 159393#0: [lua] orange.lua:76: init(): Startup error: /usr/local/orange/orange/orange.lua:68: attempt to index upvalue 'config' (a nil value)

* because the above configuration is not correct json format. i change single quotation marks to double quotation marks.so it works.

[EasonFeng5870]

LGTM

[wujunze]

LGTM

[wujunze]

Thanks @liulei18