Clarify purpose of `BlockingCollection<T>.GetConsumingEnumerable` and relationship to `Take`

I have two suggestions:
1. Add a "Remarks" section to `GetConsumingEnumerable()` that is identical to the remarks section for `GetConsumingEnumerable(CancellationToken)`. It contains several useful facts about how `GetConsumingEnumerable()` works. Putting it in the "Remarks" section for `GetConsumingEnumerable(CancellationToken)` isn't sufficient because people like me that don't care about cancellation are unlikely to look at `GetConsumingEnumerable(CancellationToken)`.
2. In the "Remarks" section for `Take`, mention that if you want to consume items in a loop, consider using `GetConsumingEnumerable` which is designed for this use case. I'm assuming that's the relationship between `Take` and `GetConsumingEnumerable`. It took some thinking on my part to infer this because it's not explicitly stated anywhere. You might also want to make a statement about `Take` in the "Remarks" section for `GetConsumingEnumerable`.

Adam Comella
Microsoft Corp.

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* ID: f8df56b2-d5da-8d38-ea9d-7f2fb50f877f
* Version Independent ID: f903165e-d4c7-939f-6679-413310730fe6
* Content: [BlockingCollection.GetConsumingEnumerable Method (System.Collections.Concurrent)](https://docs.microsoft.com/en-us/dotnet/api/system.collections.concurrent.blockingcollection-1.getconsumingenumerable?view=netframework-4.7.2#System_Collections_Concurrent_BlockingCollection_1_GetConsumingEnumerable)
* Content Source: [xml/System.Collections.Concurrent/BlockingCollection`1.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Collections.Concurrent/BlockingCollection`1.xml)
* Service: **unspecified**
* Product: **.net**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**

Öffne xml/System.Collections.Concurrent/BlockingCollection`1.xml und überprüfe die Remarks-Abschnitte für GetConsumingEnumerable(), GetConsumingEnumerable(CancellationToken) und Take. Füge die angeforderte Erklärung der parameterlosen Methode hinzu und stelle klar, wann GetConsumingEnumerable gegenüber Take in einer Schleife vorzuziehen ist. Als erledigt gilt die Aufgabe, wenn die zugehörige API-Dokumentation ihre Beziehung ausdrücklich erklärt, ohne auf die Überladungsvariante mit CancellationToken angewiesen zu sein.

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