Missing MJML config file support

[NathanBnm]

The MJML framework allows to create a .mjmlconfig file when using the CLI.
Would be great to associate the MJML icon to it.

[PKief]

I've added it 😊

Until the next update arrives on the Marketplace you can paste the following config to your user settings to enable it immediately:

"material-icon-theme.files.associations": {
  ".mjmlconfig": "mjml",
}

[NathanBnm]

Thanks