Introduce new overload of Enumerating() (#1431)

[mu88]

IMPORTANT

• The code complies with the Coding Guidelines for C#.
• The changes are covered by a new or existing set of unit tests which follow the Arrange-Act-Assert syntax such as is used in this example.
• If the contribution adds a feature or fixes a bug, please update the release notes, which are published on the website.
• If the contribution changes the public API the changes needs to be included by running AcceptApiChanges.ps1/AcceptApiChanges.sh.
• If the contribution affects the documentation, please include your changes in this pull request so the documentation will appear on the website.

[mu88]

Any ideas why the AppVeyor build is failing? I cannot reproduce this on my machine 🤔

[jnyrup]

Thanks for working on this, looks good to me.

Can I ask you to make two additional changes:

• Update docs\_pages\releases.md with a line about the added overloads
• Add an example in docs\_pages\exceptions.md just below the func.Enumerating().Should().Throw<ArgumentException>(); example