Add Volume Attach fix

Author: bbiggerr

src/content/changelog/4-86-0-2021-03-09.md

@@ -34,3 +34,5 @@ changelog:
 ### Fixed
 
 - A bug has been fixed that prevented correct filtering for the Service Transfers List ([GET /account/service-transfers](https://linode.com/docs/api/account/#service-transfers-list)) endpoint `is_sender` property.
+
+- The Volume Attach ([POST /volumes/{volumeId}/attach](https://www.linode.com/docs/api/volumes/#volume-attach)) endpoint erroneously marked the `linode_id` property as nullable and required. This has been corrected to state that the property is optional and only accepts an integer .