Add readme to NuGet package

Author: xoofx

readme.md

@@ -1,6 +1,6 @@
 # Monocypher<font color="FF8C44">.NET</font> [![Build Status](https://github.com/xoofx/Monocypher.NET/workflows/managed/badge.svg?branch=master)](https://github.com/xoofx/Monocypher.NET/actions) [![Build Status](https://github.com/xoofx/Monocypher.NET/workflows/native/badge.svg?branch=master)](https://github.com/xoofx/Monocypher.NET/actions) [![NuGet](https://img.shields.io/nuget/v/Monocypher.svg)](https://www.nuget.org/packages/Monocypher)
 
-<img align="right" width="160px" height="160px" src="img/monocypher_dotnet.png">
+<img align="right" width="160px" height="160px" src="https://raw.githubusercontent.com/xoofx/Monocypher.NET/master/img/monocypher_dotnet.png">
 
 Monocypher.NET is a managed wrapper around [Monocypher](https://github.com/LoupVaillant/Monocypher) cryptographic library.
 
@@ -92,7 +92,7 @@ That being said, if you are building an IoT project using the C Monocypher and y
 
 ## How to Build?
 
-You need to install the [.NET 5 SDK](https://dotnet.microsoft.com/download/dotnet/5.0). Then from the root folder:
+You need to install the [.NET 6 SDK](https://dotnet.microsoft.com/download/dotnet/6.0). Then from the root folder:
 
 ```console
 $ dotnet build src -c Release

src/Monocypher/Monocypher.csproj

@@ -12,6 +12,7 @@
     <PackageProjectUrl>https://github.com/xoofx/Monocypher.NET</PackageProjectUrl>
     <PackageLicenseExpression>BSD-2-Clause</PackageLicenseExpression>
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <PackageReadmeFile>readme.md</PackageReadmeFile>
 
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>$(NoWarn);CS1591;CS0419;CS1734;CS1572;CS1573;CS1574</NoWarn>
@@ -24,6 +25,7 @@
 
   <ItemGroup>
     <None Include="../../img/monocypher_dotnet.png" Pack="true" PackagePath="" />
+    <None Include="../../readme.md" Pack="true" PackagePath="/"/>
   </ItemGroup>
 
   <ItemGroup>