Add links to Nuget resources (#18135)

docs/core/tools/dotnet-pack.md

@@ -1,7 +1,7 @@
 ---
 title: dotnet pack command
 description: The dotnet pack command creates NuGet packages for your .NET Core project.
-ms.date: 02/14/2020
+ms.date: 04/28/2020
 ---
 # dotnet pack
 
@@ -172,8 +172,14 @@ Web projects aren't packable by default. To override the default behavior, add t
   dotnet pack --runtime win10-x64
   ```
 
-- Pack the project using a [.nuspec file](https://docs.microsoft.com/nuget/reference/msbuild-targets#packing-using-a-nuspec):
+- Pack the project using a *.nuspec* file:
 
   ```dotnetcli
   dotnet pack ~/projects/app1/project.csproj -p:NuspecFile=~/projects/app1/project.nuspec -p:NuspecBasePath=~/projects/app1/nuget
   ```
+
+  For information about how to use `NuspecFile`, `NuspecBasePath`, and `NuspecProperties`, see the following resources:
+
+  - [Packing using a .nuspec](https://docs.microsoft.com/nuget/reference/msbuild-targets#packing-using-a-nuspec)
+  - [Advanced extension points to create customized package](https://docs.microsoft.com/nuget/reference/msbuild-targets#advanced-extension-points-to-create-customized-package)
+  - [Global properties](https://docs.microsoft.com/visualstudio/msbuild/msbuild-properties?view=vs-2019#global-properties)