Add comment about the missing MSBuild NuGet package path variable

Author: 0xced

src/Serilog.Formatting.Log4Net.csproj

@@ -71,6 +71,7 @@
   <Target Name="WritePackageVersionForGitHubActions" AfterTargets="Pack" Condition="$(GITHUB_OUTPUT) != ''">
     <ItemGroup>
       <GitHubOutput Include="version=$(PackageVersion)" />
+      <!-- No property is provided for the NuGet package file path, see https://github.com/NuGet/Home/issues/6671 -->
       <GitHubOutput Include="nupkg-filename=$(PackageId).$(PackageVersion).nupkg" />
     </ItemGroup>
     <WriteLinesToFile File="$(GITHUB_OUTPUT)" Lines="@(GitHubOutput)" />