message: actually fix request header example
diff: @@ -1191,12 +1191,12 @@ Additionally, applying this extension to a schema forces the schema to become a
  ```json
  "parameters": [
  {
  - "x-ms-meta": {
  + "name": "x-ms-meta",
  + "in": "header",
  "type": "string",
  - "x-ms-client-name": "Metadata",
  + "x-ms-parameter-location": "method",
  "x-ms-header-collection-prefix": "x-ms-meta-"
  }
  - }
  ]
  ```
  