Sample request: retrieving related work items

[CodeRunRepeat]

This issue is effectively reopening #113, resolved by a sample in the Snippets folder that does not exist any more.

Requesting a sample that shows how to retrieve related work items, such as the parent, children, successor, etc.

[WTobor]

I think that https://github.com/microsoft/azure-devops-dotnet-samples/blob/master/ClientLibrary/Samples/WorkItemTracking/WorkItemsSample.cs#L545 is the correct url for that sample :)