Update openapi.yml to include recent attributes from the topology

[italovalcy]

Hi,

Looking into the Kytos-ng Topology Schema (https://github.com/kytos-ng/topology/blob/master/openapi.yml#L571-L692) I don't see Link.metadata. Maybe other attributes are also missing.

Additionally, maybe we should consider migrating some of the metadata information into the OpenAPI schema. I mean the ones listed in https://kytos-ng.github.io/napps/metadata.html

[viniarck]

Indeed, Italo. Thanks for reporting this.

The openapi.yml spec needs to be updated accordingly.

Regarding reserved metadata (and internal reserved metadata), speaking of which we still need to cover validations #51. It's a possibility to move to a description section indeed, let's keep this in mind, and see how we'll go about it.