Update DateInterval for better understanding of Properties

[MicahBCode]

From manual page: https://php.net/class.dateinterval

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Please add the value ranges to the properties where applicable. In my case the reading of the documentation caused a bug as I was comparing the dates "2023-12-31" with "2024-01-31" which caused the d-Property to become 0 instead of 31 (what I expected). When investigating the issue I only realized that I should use the days-Property instead.

Adding the value ranges helps to realize that on the first sight.