This will likely be supported in future releases through Swagger 2.0 vendor extensions.
"externalDocs" at operation level is the only thing from the Swagger 2.0 spec that even comes close, but it only allows user to put a single link ... where as the API Management "documentation" tab allows the user to put multiple links and attachments.
As of version 4.0.1.0, this is not supported.
This will likely be supported in future releases through Swagger 2.0 vendor extensions.
"externalDocs" at operation level is the only thing from the Swagger 2.0 spec that even comes close, but it only allows user to put a single link ... where as the API Management "documentation" tab allows the user to put multiple links and attachments.
In the meantime you would have to use the UI.