Missing doc for subresources / Links

[mrossard]

Hi,

I'm trying to figure out how to use custom URIs with multiple parameters on ApiResources that are not doctrine entities, and the doctrine-only examples from the subresources documentation don't help much - figuring out if i'm doing something wrong or if ""Unable to generate an IRI for the item" is actually a bug requires digging pretty hard into the code of the framework, which is not much fun.

Since the latest version of api platform encourages decoupling, it'd be nice to get more generic examples, especially for new/reworked features.

For example the ApiPlatform\Metadata\Link class accepts 8 parameters; only 4 of them are mentionned in the documentation, and i couldn't find any description of how they interact with each other.

Thanks for the work though, I love working with api-platform most of the time!