[api] How to use images in api properly?

[yousefmansy1]

Describe the bug
Using this site to convert to base 64, I run a sample post with image data and on discord no file is sent at all, and on telegram only a malformed file is sent. (downloading it and changing the extension makes it work as an image again, so the data is fine.)

Original PR, does not have any example. #1993

To Reproduce

DATA=$(cat << EOF
{
	"username": "test",
	"text": "test",
	"gateway": "test",
	"event": "",
	Extra" : {
		"file": [
			{
				"Data": ["BASE64DATA"]
			}
		]
	}
}
EOF

)

curl -XPOST -H 'Content-Type: application/json'  -d "$DATA" http://localhost:4242/api/message#

Expected behavior
Image should show, but it does not.

Screenshots/debug logs

Environment (please complete the following information):

• linux/docker

Additional context

[api]
	[api.myapi]
		BindAddress="172.22.0.111:4242"
		Buffer=1000
		
		
....

[[gateway]]
name="test"
enable=true
	[[gateway.in]]
	account="api.myapi"
	channel="api"

[tehsu]

Do it like this instead,

         ```

'Extra':{
'file': [
{'Data': file,
'Name': 'filename.jpeg',
'Comment': message
}
]
}