Enable CS1591: Missing XML comment for publicly visible type or member

Author: Youssef1313

Directory.Build.props

@@ -1,4 +1,9 @@
 <Project>
+  <PropertyGroup>
+    <!-- This needs to happen before importing Arcade props. -->
+    <!-- Otherwise, Arcade would have already included 1591 in NoWarn -->
+    <SkipArcadeNoWarnCS1591>true</SkipArcadeNoWarnCS1591>
+  </PropertyGroup>
 
   <Import Project="Sdk.props" Sdk="Microsoft.DotNet.Arcade.Sdk" />
   <Import Project="$(RepositoryEngineeringDir)Analyzers.props" />
@@ -18,9 +23,8 @@
         not report warnings for missing comments.
 
         CS1573: Parameter 'parameter' has no matching param tag in the XML comment for 'parameter' (but other parameters do)
-        CS1591: Missing XML comment for publicly visible type or member 'Type_or_Member'
       -->
-    <NoWarn>$(NoWarn),1573,1591</NoWarn>
+    <NoWarn>$(NoWarn),1573</NoWarn>
   </PropertyGroup>
 
   <!-- The TFMs to build and test against. -->