convert yaml links to md, api-overview

Author: Nadia-JSch

docs/integration/api-overview.mdx

@@ -15,9 +15,9 @@ The current version of the API is hosted at [api.device42.com](https://api.devic
 
 You can find the previous versions of our Swagger (OpenAPI) YAML files below:
 
-- [v19.05.10](/assets/files/d42-swagger-v190510.yaml)
-- [v19.04.30](/assets/files/d42-swagger-v190430.yaml)
-- [v19.03.10](/assets/files/d42-swagger-v190310.yaml)
-- [v19.02.00](/assets/files/d42-swagger-v190200.yaml)
-- [v19.01.00](/assets/files/d42-swagger-v190100.yaml)
-- [v19.00.00](/assets/files/d42-swagger-v190000.yaml)
+- <a href="/assets/files/d42-swagger-v190510.yaml" download>v19.05.10</a>  
+- <a href="/assets/files/d42-swagger-v190430.yaml" download>v19.04.30</a>  
+- <a href="/assets/files/d42-swagger-v190310.yaml" download>v19.03.10</a>  
+- <a href="/assets/files/d42-swagger-v190200.yaml" download>v19.02.00</a>  
+- <a href="/assets/files/d42-swagger-v190100.yaml" download>v19.01.00</a>  
+- <a href="/assets/files/d42-swagger-v190000.yaml" download>v19.00.00</a>