Pouch start fail cause unknown flag "path" in runtime config

[Shawnpku]

Ⅰ. Issue Description

Pouch can not start after I edit the config file.

Ⅱ. Describe what happened

Pouch can not start after I add runtime config in /etc/pouch/config.json

error info:

Error: failed to load daemon file: unknown flags: path
ERRO[0000] failed to load daemon file: unknown flags: path

Ⅲ. Describe what you expected to happen

Pouch started and runv is available.

Ⅳ. How to reproduce it (as minimally and precisely as possible)

config.json:
{
"runtimes": {
    "runv": {
      "path": "runv"
       }
    }
}

Ⅴ. Anything else we need to know?

Not support "path"? Then what should I use. This config is from runv official site and If I use runv directly it will say

message:"unknown runtime runv"

Ⅵ. Environment:

• pouch version (use pouch version):1.0.0-rc1
• OS (e.g. from /etc/os-release):centos 7
• Kernel (e.g. uname -a):
• Install tools:
• Others:

[pouchrobot]

Thanks for your contribution. 🍻 @Shawnpku
While we thought ISSUE TITLE could be more specific, longer than 20 chars.
Please edit issue title instead of opening a new one.
More details, please refer to https://github.com/alibaba/pouch/blob/master/CONTRIBUTING.md

[allencloud]

Thanks for your feedback. @Shawnpku
I think this issue is related to #2081.
And we already had a pull request from @Ace-Tang to fix this #2085.
Please help check this. If what I said is something wrong, please tell me.

[Ace-Tang]

@allencloud , @Shawnpku 's problem is not related with runtime args can not be config, it about the config format, please format like:

{
	"add-runtime": {
		"runsc": {
			"path": "/usr/local/bin/runsc"
		}
	}
}

[Shawnpku]

@Ace-Tang Yes, this works. Just can not see the correct runtime config format at any docs.

[Ace-Tang]

@Shawnpku , sorry for that, I will add doc for that soon.