message: Added documentation for extension "x-ms-error-response"
diff: @@ -17,6 +17,7 @@ The following documents describes AutoRest specific vendor extensions for [OpenA
  * [x-ms-parameterized-host](#x-ms-parameterized-host) - replaces the fixed host with a host template that can be replaced with variable parameters.
  * [x-ms-mutability](#x-ms-mutability) - provides insight to Autorest on how to generate code. It doesn't alter the modeling of what is actually sent on the wire.
  * [x-ms-examples](#x-ms-examples) - describes the format for specifying examples for request and response of an operation in an OpenAPI definition.
  +* [x-ms-error-response](#x-ms-error-response) - indicates whether the response status code should be treated as an error response
  ### Microsoft Azure Extensions (available in most generators only when using `--azure-arm`)
  * [x-ms-odata](#x-ms-odata) - indicates the operation includes one or more [OData](http://www.odata.org/) query parameters.
  @@ -703,6 +704,55 @@ When present the `x-ms-odata` extensions indicates the operation includes one or
  }
  ```
  +## x-ms-error-response
  +Indicates whether the response status code should be treated as an error response or not.
  +
  +**Parent element**: [Response Object](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#response-object)
  +
  +**Schema**:
  +`true|false`
  +
  +**Example**:
  +```json5
  +. . .
  + "responses": {
  + "200": {
  + "description": "",
  + "schema": {
  + "$ref": "#/definitions/Pet"
  + }
  + },
  + "202": {
  + "description": "something something dark side"
  + },
  + "404": {
  + "description": "Not found",
  + "schema": {
  + "$ref": "#/definitions/NotFoundErrorBase"
  + },
  + "x-ms-error-response": true
  + },
  + "400": {
  + "description": "Bad request",
  + "schema": {
  + "type": "string"
  + },
  + "x-ms-error-response": true
  + },
  + "501": {
  + "description": "Some unexpected error",
  + "schema": {
  + "type": "integer"
  + },
  + "x-ms-error-response": true
  + },
  + "default": {
  + "description": "default stuff"
  + }
  + }
  +. . .
  +```
  +
  ## x-ms-pageable
  The REST API guidelines define a common pattern for paging through lists of data. The operation response is modeled in OpenAPI as a list of items (a "page") and a link to the next page, effectively resembling a singly linked list. Tag the operation as `x-ms-pageable` and the generated code will include methods for navigating between pages.
  