[#75691732] Document vcloud-core public methods

> According to semver http://semver.org/ we should document the API
> (lower case should). We should document this by adding Yard
> documentation to public methods. See [#73962736] for an example.
Could add a little bit of detail, i.e. this is to shield users https://github.com/gds-operations/vcloud-core/commit/613d6fd3ce1859bf76dd506dd2e0ad9a07da2f72?