dashboard nebula-httpd show null

[Reid00]

Since dashboard nebula-httpd port 8090 show null is confused, i want to submit pull request change the response with below:
{
"code": 0,
"data": "Run Successfully!",
"message": "Welcome Nebula-Http-GateWay!"
}
Is this ok?

[wey-gu]

@Reid00 Thanks so much!

@hetao92 what do you think? maybe a discussion on the wording first here then @Reid00 could go ahead on the PR ;-).

[wey-gu]

@Reid00 , just talked with @hetao92 , it's great to have your PR on this, could you kindly help with it?
Thanks!!!

[Reid00]

@wey-gu have submitted PR, please review it.

[hetao92]

added