Missing CS8955 Error Code Documentation

### Type of issue

Missing information for CS8955

### Description

Sample Code:

```
namespace SampleNamespace
{
namespace Nested;
}
```

Missing documentation on this Error code for nested namespaces.

### Page URL

https://learn.microsoft.com/en-us/dotnet/csharp/misc/sorry-we-don-t-have-specifics-on-this-csharp-error?f1url=%3FappId%3Droslyn%26k%3Dk(CS8955)

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/csharp/misc/sorry-we-don-t-have-specifics-on-this-csharp-error.md

### Document Version Independent Id

58a19505-ac46-c5c8-12cc-fe87b6aa18a7

### Article author

@BillWagner

### Metadata

* ID: bbb051ee-f020-66ba-c601-4a08ad32ef61
* Service: **dotnet-csharp**
* Sub-service: **errors-warnings**

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