How to change ice_servers with credential details in config.json

[sraza295]

{
"server": {
"http_port": ":8888",
"ice_servers": ["stun:stun.l.google.com:19302"]
},
"streams": {
"INSTAR_IN-6014_HD": {
"on_demand": true,
"url": "rtsp://admin:instar@192.168.2.47/11"
},
"INSTAR_8015_FHD": {
"on_demand": true,
"url": "rtsp://admin:instar@192.168.2.77/11"
},
"INSTAR_9020_FHD": {
"on_demand": true,
"url": "rtsp://admin:instar@192.168.2.117/12"
},
"INSTAR_IN-7011_HD": {
"on_demand": true,
"url": "rtsp://admin:instar@192.168.2.63/11"
},
"H264_PCMALAW": {
"on_demand": true,
"url": "rtsp://admin:evro0811@89.21.77.183:33556/"
}
}
}

Now, how do I change "ice_servers" with credentials?
For example this is my turn server : {
url: 'turn:numb.viagenie.ca',
credential: 'muazkh',
username: 'webrtc@live.com'
}

how to change in config.json