[kotlin] cleanup documentation (#15307)

* [kotlin] fix documentation of API authorization in README files

fix hierarchy level + add internal links + align wording across generators

* [kotlin] fix anchor links in documentation

---------

Co-authored-by: Tiffany Marrel <tiffany.marrel@flowable.com>

samples/client/petstore/kotlin-enum-default-value/README.md

@@ -37,7 +37,7 @@ This runs all tests and packages the library.
 * Some Kotlin and Java types are fully qualified to avoid conflicts with types defined in OpenAPI definitions.
 * Implementation of ApiClient is intended to reduce method counts, specifically to benefit Android targets.
 
-<a name="documentation-for-api-endpoints"></a>
+<a id="documentation-for-api-endpoints"></a>
 ## Documentation for API Endpoints
 
 All URIs are relative to *http://localhost*
@@ -47,13 +47,14 @@ Class | Method | HTTP request | Description
 *DefaultApi* | [**operation**](docs/DefaultApi.md#operation) | **GET** / | 
 
 
-<a name="documentation-for-models"></a>
+<a id="documentation-for-models"></a>
 ## Documentation for Models
 
  - [org.openapitools.client.models.ModelWithEnumPropertyHavingDefault](docs/ModelWithEnumPropertyHavingDefault.md)
 
 
-<a name="documentation-for-authorization"></a>
+<a id="documentation-for-authorization"></a>
 ## Documentation for Authorization
 
-All endpoints do not require authorization.
+Endpoints do not require authorization.
+

samples/client/petstore/kotlin-enum-default-value/docs/DefaultApi.md

@@ -7,7 +7,7 @@ Method | HTTP request | Description
 [**operation**](DefaultApi.md#operation) | **GET** / | 
 
 
-<a name="operation"></a>
+<a id="operation"></a>
 # **operation**
 > ModelWithEnumPropertyHavingDefault operation()
 

samples/client/petstore/kotlin-enum-default-value/docs/ModelWithEnumPropertyHavingDefault.md

@@ -7,7 +7,7 @@ Name | Type | Description | Notes
 **propertyName** | [**inline**](#PropertyName) |  | 
 
 
-<a name="PropertyName"></a>
+<a id="PropertyName"></a>
 ## Enum: propertyName
 Name | Value
 ---- | -----