separate class for getting IEnumerator or implementation IEnumerator inside are not needed

Making PeopleEnum class is not needed, when you use foreach without custom sort of output. Instead of it just call GetEnumerator() from _people. _people - is array of Person objects. And arrays of any kind of object have GetEnumerator method.
Write public IEnumerator GetEnumerator() in next way:
{
return _people.GetEnumerator();
}
Class PeopleEnumClass is not needed and may be deleted.

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#### Document Details

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* ID: 87006da9-9d40-cb2e-b516-715ea36cdbea
* Version Independent ID: 5c32a764-8844-e344-a42b-8dd1177fa32f
* Content: [IEnumerable Interface (System.Collections)](https://docs.microsoft.com/en-us/dotnet/api/system.collections.ienumerable?f1url=https%3A%2F%2Fmsdn.microsoft.com%2Fquery%2Fdev15.query%3FappId%3DDev15IDEF1%26l%3DEN-US%26k%3Dk(System.Collections.IEnumerable);k(TargetFrameworkMoniker-.NETFramework,Version%3Dv4.7.1);k(DevLang-csharp)%26rd%3Dtrue&view=netframework-4.7.2)
* Content Source: [xml/System.Collections/IEnumerable.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Collections/IEnumerable.xml)
* Product: **dotnet-api**
* GitHub Login: @mairaw
* Microsoft Alias: **mairaw**