#2199 use repo readme for base package readme (#2200)

Author: thompson-tomo

src/Confluent.Kafka/Confluent.Kafka.csproj

@@ -10,6 +10,7 @@
     <PackageReleaseNotes>https://github.com/confluentinc/confluent-kafka-dotnet/releases</PackageReleaseNotes>
     <PackageTags>Kafka;Confluent;librdkafka</PackageTags>
     <PackageId>Confluent.Kafka</PackageId>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
     <Title>Confluent.Kafka</Title>
     <AssemblyName>Confluent.Kafka</AssemblyName>
     <VersionPrefix>2.3.0</VersionPrefix>
@@ -35,4 +36,8 @@
     <PackageReference Include="System.Threading" Version="4.3.0" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Include="..\..\README.md" Pack="true" PackagePath="\" />
+  </ItemGroup>
+
 </Project>