added SourceLink.Github support (#166)

* added SourceLink.Github support

* added SourceLink metadata

* made SourceLink a private asset

Author: Aaronontheweb

src/common.props

@@ -24,4 +24,17 @@ For a set of complete bug fixes and changes, please see [the HOCON v1.2.1 milest
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
     <DefineConstants>$(DefineConstants);NETCORE</DefineConstants>
   </PropertyGroup>
+  <PropertyGroup>
+    <!-- Optional: Publish the repository URL in the built .nupkg (in the NuSpec <Repository> element) -->
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+ 
+    <!-- Optional: Embed source files that are not tracked by the source control manager in the PDB -->
+    <EmbedUntrackedSources>true</EmbedUntrackedSources>
+  
+    <!-- Optional: Build symbol package (.snupkg) to distribute the PDB containing Source Link -->
+    <IncludeSymbols>true</IncludeSymbols>
+  </PropertyGroup>
+    <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
+  </ItemGroup>
 </Project>