Added comment to GetTargetPath.

Author: MiYanni

src/Tasks/sdk-tasks/sdk-tasks.csproj

@@ -37,6 +37,10 @@
     <Using Include="Microsoft.Build.Utilities.Task" Alias="Task" />
   </ItemGroup>
 
+  <!--
+    Encountered an error about this target being missing when rebuilding within VS.
+    See: https://github.com/dotnet/msbuild/issues/4303#issuecomment-482345617
+  -->
   <Target Name="GetTargetPath" />
 
 </Project>