Update CS0193 error message documentation for function pointers

[Copilot]

This PR updates the documentation for compiler error CS0193 to provide more clarity regarding function pointers.

The changes:

• Modified the error message to specify "data pointer" instead of just "pointer" to clarify that function pointers are excluded
• Added an explanation that function pointers cannot be dereferenced in C#, unlike in C/C++
• Included a code example demonstrating the error when attempting to dereference a function pointer
• Added a reference to the function pointers documentation

These changes address confusion for developers who are familiar with C/C++ where dereferencing function pointers is valid syntax.

Example of the issue:

unsafe class Example
{
    public static void Log() { }
    
    public static unsafe void Main()
    {
        delegate*<void> fp = &Log;   // pointer to managed function Log()
        fp();                        // OK; call Log() via function pointer
        (*fp)();                     // Error; CS0193, function pointers cannot be dereferenced
    }
}

Fixes #46398.

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Internal previews

📄 File	🔗 Preview link
docs/csharp/misc/cs0193.md	Compiler Error CS0193

[BillWagner]

Hi @copilot

Once you fix the date, this is ready to merge.

[Copilot]

Hi @copilot

Once you fix the date, this is ready to merge.

I've updated the ms.date field to 05/27/2025 as requested in commit 957ce08.

[BillWagner]

Thanks @copilot

and @yufeih

This LGTM, and I'll now.