Update GetDelegateForFunctionPointer docs (#3707)

Author: nxtn

xml/System.Runtime.InteropServices/Marshal.xml

@@ -3090,17 +3090,15 @@
 
  In the .NET Framework 2.0 and later versions, you can use the <xref:System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer%2A> and <xref:System.Runtime.InteropServices.Marshal.GetFunctionPointerForDelegate%2A> methods to marshal delegates in both directions. With <xref:System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer%2A>, `ptr` is imported as a <xref:System.IntPtr?displayProperty=nameWithType>. A <xref:System.IntPtr?displayProperty=nameWithType> can be obtained for a managed delegate by calling <xref:System.Runtime.InteropServices.Marshal.GetFunctionPointerForDelegate%2A> and passed as a parameter; it can then be called from inside the unmanaged method. Note that the parameter marshaler can also marshal function pointers to delegates in the .NET Framework 2.0 and later versions.  
 
- The <xref:System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer%2A> method has the following restrictions:  
+  `ptr` is converted to a delegate that invokes the unmanaged method using the [__stdcall](/cpp/cpp/stdcall) calling convention on Windows, or the [__cdecl](/cpp/cpp/cdecl) calling convention on Linux and macOS. You can set the calling convention by applying the <xref:System.Runtime.InteropServices.UnmanagedFunctionPointerAttribute> to the delegate.
 
--   Generics are not supported in interop scenarios.  
+ The <xref:System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer%2A> method has the following restrictions:  
 
--   You cannot pass an invalid function pointer to this method.  
+-   Generics are not supported in interop scenarios.   
 
 -   You can use this method only for pure unmanaged function pointers.  
 
--   You cannot use this method with function pointers obtained through C++ or from the <xref:System.RuntimeMethodHandle.GetFunctionPointer%2A> method.  
-  
--   You cannot use this method to create a delegate from a function pointer to another managed delegate.  
+-   You cannot use this method with function pointers obtained through C++.  
 
  ]]></format>
         </remarks>
@@ -3167,15 +3165,15 @@
 ## Remarks  
  You can use the <xref:System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer%60%601%28System.IntPtr%29> and <xref:System.Runtime.InteropServices.Marshal.GetFunctionPointerForDelegate%60%601%28%60%600%29> methods to marshal delegates in both directions.  
 
+  `ptr` is converted to a delegate that invokes the unmanaged method using the [__stdcall](/cpp/cpp/stdcall) calling convention on Windows, or the [__cdecl](/cpp/cpp/cdecl) calling convention on Linux and macOS. You can set the calling convention by applying the <xref:System.Runtime.InteropServices.UnmanagedFunctionPointerAttribute> to the delegate.
+  
  The <xref:System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer%60%601%28System.IntPtr%29> method has the following restrictions:  
 
--   You cannot pass an invalid function pointer to this method.  
+-   Generics are not supported in interop scenarios.   
 
 -   You can use this method only for pure unmanaged function pointers.  
 
--   You cannot use this method with function pointers obtained through C++ or from the <xref:System.RuntimeMethodHandle.GetFunctionPointer%2A> method.  
-  
--   You cannot use this method to create a delegate from a function pointer to another managed delegate.  
+-   You cannot use this method with function pointers obtained through C++.  
 
  ]]></format>
         </remarks>