F1 on `global` keyword of a `global using` directive opens the wrong help page

**Version Used**: VS 17.6 P5

**Steps to Reproduce**:
Press F1 on the `global` keyword.
```csharp
global using System;
```

**Expected Behavior**:
The [help page for using directives](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-directive) is opened, which has a section on the `global` modifier.

**Actual Behavior**:
The [help page for the namespace alias operator](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/namespace-alias-qualifier) is opened, which explains the usage of `global` as a namespace alias.