fix null format (#3640)

Author: mairaw

xml/Microsoft.Aspnet.Snapin/IDataObject.xml

@@ -216,7 +216,7 @@ For more information about programming with the <xref:Microsoft.Aspnet.Snapin.ID
       </Parameters>
       <Docs>
         <param name="a">A pointer to the <see cref="T:Microsoft.Aspnet.Snapin.FORMATETC" /> defining the format, medium, and target device for calls to retrieve data.</param>
-        <param name="b">An output pointer to a FORMATETC containing the most general information possible for a specific rendering or <langword name="null" />, if the GetCanonicalFormatEtc method returns DATA_S_SAMEFORMATETC.</param>
+        <param name="b">An output pointer to a FORMATETC containing the most general information possible for a specific rendering, or <see langword="null" /> if the GetCanonicalFormatEtc method returns DATA_S_SAMEFORMATETC.</param>
         <summary>Retrieves a pointer to a standard <see cref="T:Microsoft.Aspnet.Snapin.FORMATETC" /> structure that is logically equivalent to, but not necessarily equal to, the <see cref="T:Microsoft.Aspnet.Snapin.FORMATETC" /> structure that is referenced by the <paramref name="a" /> parameter.</summary>
         <returns>The GetCanonicalFormatEtc method supports the standard return values E_INVALIDARG, E_UNEXPECTED, and E_OUTOFMEMORY, as well as the following return values: