add msbuild properties for SourceLink

Author: matracey

src/Directory.Build.props

@@ -15,10 +15,14 @@
         <JsonDiffPatchPackageVersion>1.3.1</JsonDiffPatchPackageVersion>
         <Authors>Wei Chen</Authors>
         <PackageProjectUrl>https://github.com/weichch/system-text-json-jsondiffpatch</PackageProjectUrl>
+        <RepositoryUrl>https://github.com/weichch/system-text-json-jsondiffpatch.git</RepositoryUrl>
+        <RepositoryType>git</RepositoryType>
         <Copyright>Copyright © Wei Chen 2022</Copyright>
         <PackageIcon>icon.png</PackageIcon>
         <PackageLicenseFile>LICENSE</PackageLicenseFile>
         <PackageReleaseNotes>https://github.com/weichch/system-text-json-jsondiffpatch/blob/$(JsonDiffPatchPackageVersion)/ReleaseNotes.md</PackageReleaseNotes>
+        <PublishRepositoryUrl>true</PublishRepositoryUrl>
+        <EmbedUntrackedSources>true</EmbedUntrackedSources>
     </PropertyGroup>
 
     <PropertyGroup>