Enable xml documentation generation

Microsoft.Toolkit.Uwp.Connectivity/Microsoft.Toolkit.Uwp.Connectivity.csproj

@@ -90,6 +90,7 @@
     <PlatformTarget>x64</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
+    <DocumentationFile>bin\x64\Debug\Microsoft.Toolkit.Uwp.Connectivity.XML</DocumentationFile>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x64'">
     <PlatformTarget>x64</PlatformTarget>