doc: Add link to generated API docs on API page (#2460)

* doc: Add link to generated API docs on API page

This makes it easier to find the generated API docs from the API
description page.

* Update website/content/docs/api-clients/api.mdx

Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com>

Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com>

website/content/docs/api-clients/api.mdx

@@ -13,6 +13,8 @@ Before reading this page, it is useful to understand Boundary's [domain model](/
 
 Boundary's API is also described via OpenAPI v2; the version corresponding to any tag of Boundary's source code can be found in Boundary's [GitHub repository](https://github.com/hashicorp/boundary/blob/main/internal/gen/controller.swagger.json).
 
+-> **NOTE:** A rendered version of this generated API definition can be found on the [API page](/api-docs).
+
 Boundary's current API version is 1; all API paths begin with `/v1/`.
 
 ## Status Codes