message: Add support for 'unk' in OcrSkillLanguage
diff: "ro",
  "sr-Cyrl",
  "sr-Latn",
  - "sk"
  + "sk",
  + "unk"
  ],
  "x-ms-enum": {
  "name": "OcrSkillLanguage",
  {
  "value": "sk",
  "description": "Slovak"
  + },
  + {
  + "value": "unk",
  + "description": "Unknown. If the language is explicitly set to \"unk\", the language will be auto-detected."
  }
  ]
  },
  