backend snippet needs a comma between s3 and swift

[rprihoda]

Backend configuration:
  scope: meta.terraform.tf
  prefix: backend
  description: Backend configuration.
  body: |
    backend ${1|local,remote,artifactory,azurerm,consul,cos,etcd,etcdv3gcs,http,mantaoss,pg,s3swift,atlas|} {
      ${2|name,address,path,prefix,endpoints,url,scheme,username,password,token|} = "${3:value}"
    }

While testing out your plugin, I came across a typo in your backend snippet. There should be a comma between s3 and swift.