Mention DateOnly possibility in place of DateTime - update to indexers article

[mahab339]

Change ( .NET doesn't include a date-only type. Developers use the DateTime type, but use the Date property to ensure that any DateTime object from that day are equal.) to (While .NET introduces DateOnly type, this example uses the DateTime type, and uses...).

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• ID: bcc06ead-fe51-85db-1340-87f6473db769
• Version Independent ID: 4f2c312e-609c-a643-4af6-c12c6cf74738
• Content: Indexers
• Content Source: docs/csharp/indexers.md
• Product: dotnet-csharp
• Technology: csharp-fundamentals
• GitHub Login: @BillWagner
• Microsoft Alias: wiwagn

[BillWagner]

Thanks for noting this We will update this article to include the new capabilities.