add Nuget Package Readme and file (#2575)

* add Nuget Package Readme and file

Docs/NugetREADME.md

@@ -0,0 +1,36 @@
+# OPC UA .NET Standard stack documentation
+
+## Overview
+
+The OPC UA .NET Standard stack enables you to build multi-platform OPC UA Applications with rich functionality including:
+ - Server
+ - Client
+ - PubSub
+
+
+### For more information and license terms, see the projects official [Website](http://opcfoundation.github.io/UA-.NETStandard).
+
+## Getting started
+
+The reference [Client](https://github.com/OPCFoundation/UA-.NETStandard/tree/master/Applications/ConsoleReferenceClient) & [Server](https://github.com/OPCFoundation/UA-.NETStandard/tree/master/Applications/ReferenceServer) projects provide a starting point in implementing your own application.
+
+<!---
+ Simple Client:
+```C#
+ToDo
+```
+
+Simple Server:
+```C#
+ToDo
+```
+-->
+
+
+## Packages Overview
+
+Caution, there are multiple packages available with different functional scopes, for a detailed overview take a look at the [Information about the different Packages](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/Docs/PlatformBuild.md#further-information-on-the-supported-nuget-packages).
+
+## Additional documentation
+
+Additional information about the OPC UA .NET Standard stack is available on the GitHub Repo of the project in the [detailed Documentation](https://github.com/OPCFoundation/UA-.NETStandard/tree/master/Docs#opc-ua-net-standard-stack-documentation).

common.props

@@ -37,6 +37,7 @@
     <!-- deprecated <PackageLicenseUrl>https://opcfoundation.org/license/source/1.11/index.html</PackageLicenseUrl>-->
     <PackageLicenseFile>licenses/LICENSE.txt</PackageLicenseFile>
     <PackageReleaseNotes>$(RepositoryUrl)/releases</PackageReleaseNotes>
+    <PackageReadmeFile>NugetREADME.md</PackageReadmeFile>
     <PackageTags>OPCFoundation OPC UA netstandard ios linux dotnet net netcore uwp</PackageTags>
   </PropertyGroup>
 
@@ -52,6 +53,10 @@
     <None Include="$(MSBuildThisFileDirectory)/nuget/logo.jpg" Pack="true" PackagePath="$(PackageIcon)"/>
   </ItemGroup>
 
+  <ItemGroup Condition="'$(IsPackable)' != 'false'">
+    <None Include="$(MSBuildThisFileDirectory)/Docs/NugetREADME.md" Pack="true" PackagePath="$(PackageReadmeFile)"/>
+  </ItemGroup>
+
   <ItemGroup Condition="'$(NBGV_PublicRelease)' != ''">
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All"/>
   </ItemGroup>