add new rule XmsIdentifierValidation doc (#17076)

* add new rule XmsIdentifierValidation doc

* fix comment

* fix comment

* fix comment

Co-authored-by: Tianxiang Chen <[email protected]>

Author: tianxchen-ms

documentation/openapi-authoring-automated-guidelines.md

@@ -120,6 +120,7 @@ We request OpenAPI(Swagger) spec authoring be assigned to engineers who have an
 | [R4037](#r4037) | [MissingTypeObject](#r4037) | ARM and Data plan OpenAPI(swagger) specs |
 | [R4039](#r4039) | [ParametersOrder](#r4039) | ARM and Data plan OpenAPI(swagger) specs |
 | [R4040](#r4040) | [EnumMustRespectType](#r4040) | ARM and Data plan OpenAPI(swagger) specs |
+| [R4041](#r4041) | [XmsIdentifierValidation](#r4041) | ARM OpenAPI(swagger) specs |
 #### SDK Warnings
 
 | Id | Rule Name | Applies to |
@@ -3579,3 +3580,24 @@ Links: [Index](#index) | [Error vs. Warning](#error-vs-warning) | [Automated Rul
 Just change the enum value to the right type.
 
 Links: [Index](#index) | [Error vs. Warning](#error-vs-warning) | [Automated Rules](#automated-rules) | [ARM](#arm-violations): [Errors](#arm-errors) or [Warnings](#arm-warnings) | [SDK](#sdk-violations): [Errors](#sdk-errors) or [Warnings](#sdk-warnings)
+
+### <a name="r4041"></a>R4041 XmsIdentifierValidation
+
+**Category** : SDK Error
+
+**Applies to** : ARM OpenAPI(swagger) specs
+
+**Output Message** : Missing identifier {0} in array item property.
+
+**Description**: This rule is to check the `id` property or identifier of objects in the array. See more here: [x-ms-identifiers](https://github.com/Azure/autorest/tree/main/docs/extensions#x-ms-identifiers).
+
+**CreatedAt**: Decenmber 15, 2021
+
+**LastModifiedAt**: Decenmber 15, 2021
+
+**Why this rule is important**: Using [x-ms-identifiers](https://github.com/Azure/autorest/tree/main/docs/extensions#x-ms-identifiers) will provide more flexibility for array types in SDK generated code.
+
+**How to fix the violation**:
+If you don't need identifier in array, leave `x-ms-identifiers` as an empty array. Otherwise, add the identifying property in the object or correct the `x-ms-identifiers`.
+
+Links: [Index](#index) | [Error vs. Warning](#error-vs-warning) | [Automated Rules](#automated-rules) | [ARM](#arm-violations): [Errors](#arm-errors) or [Warnings](#arm-warnings) | [SDK](#sdk-violations): [Errors](#sdk-errors) or [Warnings](#sdk-warnings)