Add version history note to API template

doc/development/documentation/restful_api_styleguide.md

@@ -38,12 +38,16 @@ The following can be used as a template to get started:
 ````markdown
 ## Descriptive title
 
+> Version history note.
+
 One or two sentence description of what endpoint does.
 
 ```plaintext
 METHOD /endpoint
 ```
 
+Supported attributes:
+
 | Attribute   | Type     | Required | Description           |
 |:------------|:---------|:---------|:----------------------|
 | `attribute` | datatype | yes/no   | Detailed description. |
@@ -65,6 +69,9 @@ Example response:
 ```
 ````
 
+Adjust the [version history note accordingly](styleguide/index.md#version-text-in-the-version-history)
+to describe the GitLab release that introduced the API call.
+
 ## Method description
 
 Use the following table headers to describe the methods. Attributes should