IDE0071: misleading analyzer's description where .NET version< 6.0

[IDE0071](https://docs.microsoft.com/ru-ru/dotnet/fundamentals/code-analysis/style-rules/ide0071)


```csharp
enum Foo
{
A = 0
}

var test1 = $"Test foo = {Foo.A}."; // No diagnostic for IDE0071. But the compiler will convert the code to this with boxing: string.Format("Test foo = {0}.", Foo.A);
var test2 = $"Test foo = {Foo.A.ToString()}."; // Get diagnostic for IDE0071. But there is no boxing.
```

It may be worth correcting the description of the analyzer so that it is not misleading.

https://github.com/dotnet/roslyn/issues/55240
https://github.com/JosefPihrt/Roslynator/issues/828

[Edited to add doc details]

---
#### Document Details

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* ID: b5899d7a-30d1-32aa-a91e-6ae492e86bcf
* Version Independent ID: ba625de0-931a-eb2c-2c77-0a87a76a86f9
* Content: [IDE0071: Simplify interpolation - .NET](https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/style-rules/ide0071)
* Content Source: [docs/fundamentals/code-analysis/style-rules/ide0071.md](https://github.com/dotnet/docs/blob/main/docs/fundamentals/code-analysis/style-rules/ide0071.md)
* Product: **dotnet-fundamentals**
* GitHub Login: @gewarren
* Microsoft Alias: **gewarren**