GUID interop: ref vs [MarshalAs(UnmanagedType.LPStruct)] is confusing

### Type of issue

Typo

### Description

#### Current wording
"❌ DON'T Use `[MarshalAs(UnmanagedType.LPStruct)]` for anything other than `ref` GUID parameters."

This does not make sense, when reading the paragraph above that says "place either a `ref` keyword or a `[MarshalAs(UnmanagedType.LPStruct)]` attribute on the GUID parameter declaration"

#### Paragraph above current wording

"GUIDs are usable directly in signatures. Many Windows APIs take `GUID&` type aliases like `REFIID`. When the method signature contains a reference parameter, place either a `ref` keyword or a `[MarshalAs(UnmanagedType.LPStruct)]` attribute on the GUID parameter declaration."

### Page URL

https://learn.microsoft.com/en-us/dotnet/standard/native-interop/best-practices#guids

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/standard/native-interop/best-practices.md

### Document Version Independent Id

e58f3d16-8083-0efe-0057-e21dbebb262f

### Platform Id

87721c9b-7c82-1598-5dfd-21d35f0beec8

### Article author

@jkoritzinsky

### Metadata

* ID: 6ea501d3-d963-c5dc-342d-ee82c92d1850
* PlatformId: 87721c9b-7c82-1598-5dfd-21d35f0beec8
* Service: **dotnet-fundamentals**

[Related Issues](https://github.com/dotnet/docs/issues?q=is%3Aissue+is%3Aopen+e58f3d16-8083-0efe-0057-e21dbebb262f)