add package README.md to make NuGet happier (#2875)

links are intentionally duplicated; IIRC the release notes MD processor is fairly restricted

Author: mgravell

src/StackExchange.Redis/README.md

@@ -0,0 +1,6 @@
+StackExchange.Redis is a high-performance RESP (Redis, etc) client for .NET, available under the MIT license.
+
+- Release notes: [https://stackexchange.github.io/StackExchange.Redis/ReleaseNotes](https://stackexchange.github.io/StackExchange.Redis/ReleaseNotes)
+- NuGet package: [https://www.nuget.org/packages/StackExchange.Redis/](https://www.nuget.org/packages/StackExchange.Redis/)
+- General docs: [https://stackexchange.github.io/StackExchange.Redis/](https://stackexchange.github.io/StackExchange.Redis/)
+- Code: [https://github.com/StackExchange/StackExchange.Redis/](https://github.com/StackExchange/StackExchange.Redis/)

src/StackExchange.Redis/StackExchange.Redis.csproj

@@ -12,6 +12,7 @@
     <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
     <DefineConstants Condition="'$(TargetFramework)' != 'net461'">$(DefineConstants);VECTOR_SAFE</DefineConstants>
     <DefineConstants Condition="'$(TargetFramework)' != 'net461' and '$(TargetFramework)' != 'net472' and '$(TargetFramework)' != 'netstandard2.0'">$(DefineConstants);UNIX_SOCKET</DefineConstants>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
   </PropertyGroup>
 
   <ItemGroup>
@@ -28,6 +29,8 @@
 
     <!-- netfx needs this for ZipArchive -->
     <PackageReference Include="System.IO.Compression" Condition="'$(TargetFramework)' == 'net472' or '$(TargetFramework)' == 'net461' " />
+
+    <None Include="README.md" Pack="true" PackagePath="\"/>
   </ItemGroup>
 
   <ItemGroup>