Update comments

Author: edvilme

src/Cli/dotnet/NugetPackageDownloader/NuGetPackageDownloader.cs

@@ -38,6 +38,10 @@ internal class NuGetPackageDownloader : INuGetPackageDownloader
         private readonly Dictionary<PackageSource, SourceRepository> _sourceRepositories;
         private readonly bool _shouldUsePackageSourceMapping;
 
+        /// <summary>
+        /// If true, the package downloader will verify the signatures of the packages it downloads.
+        /// Temporarily disabled for macOS and Linux. 
+        /// </summary>
         private readonly bool _verifySignatures;
         private readonly VerbosityOptions _verbosityOptions;
         private readonly string _currentWorkingDirectory;