Ensure that usage/registration of custom URL resolver is clear enough

[MiroKentico]

In the past, developer wanted to register and use custom implementation of custom URL resolver based on https://kontent.ai/learn/tutorials/develop-apps/get-content/structured-rich-text/?tech=dotnet#a-resolve-hyperlinks-to-content-items.

Unfortunately his implementation combined usage of DeliveryClientBuilder methods WithContentLinkUrlResolver and WithModelProvider. Developer expectation was, that custom URL resolver set by WithContentLinkUrlResolver will be used, but that didn't happen. It seems that root cause of this was, that his custom model provider set by WithModelProvider internally used different collection of URL resolvers (maybe even empty ?).

I would like to check and ensure that the implementation of this URL resolver usage code is clear, and so it should be our Wiki. Maybe just a simple note on this topic added into our Wiki might prevent similar situations in future.

[Simply007]

might be related to #312