Offline ComWrappers Tutorial feedback

Author: AaronRobinsonMSFT

xml/System.Runtime.InteropServices/ComWrappers.xml

@@ -203,7 +203,15 @@ If the object cannot be created and `null` is returned, the call to <xref:System
         <param name="fpAddRef">Function pointer to AddRef.</param>
         <param name="fpRelease">Function pointer to Release.</param>
         <summary>Gets the runtime-provided IUnknown implementation.</summary>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The runtime implementations of these `IUnknown` functions are all thread-safe. Each of them is optimized and strictly follows the COM rules for `IUnknown`. The `QueryInterface` implementation also respects the <xref:System.Runtime.InteropServices.ICustomQueryInterface> interface. The `ICustomQueryInterface` interface will never have an opportunity to override interfaces that the runtime provides. For example, by default the runtime provides the  `IUnknown` interface and, optionally, the Reference Tracker `IReferenceTrackerTarget` interface.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="GetOrCreateComInterfaceForObject">