This PR contains the work done to declare the missing, non-GET endpoints of the *Database* section in the [Discogs API documentation](https://www.discogs.com/developers#page:database) into the `OpenAPI` specification document.
Furthermore, documentation extensions have been defined for the `APIProtocol` and `Client` types in the `DocC` documentation catalog to match the categories of these endpoint calls to the categories in the Discogs documentation.
Reviewed-on: #8
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>
javier