Add changelog to SDK version 5.0.0 (#15073)

* add changelog to version 5.0.0

* nit

* update changelog and add release date

sdk/servicebus/Microsoft.Azure.ServiceBus/CHANGELOG.md

@@ -1,6 +1,11 @@
 # Release History
-## 4.1.4 (2020-08-05)
-- Setting sessionId to be same as partition key and adding validation
+## 5.0.0 (2020-09-11)
+### Breaking Changes
+- Setting sessionId to be same as partition key and adding validation [PR 13961](https://github.com/Azure/azure-sdk-for-net/pull/13961)
+
+### Improvements
+- Enable a way to Unregister Message Handler and Session Handler [PR 14021](https://github.com/Azure/azure-sdk-for-net/pull/14021)
+- Documentation: Add `SendAsync` warning for partition entities when batching is enabled [PR 14021](https://github.com/Azure/azure-sdk-for-net/pull/11028)
 
 ## 4.1.3 (2020-04-17)
 - Add `GetQueuesRuntimeInfoAsync`, `GetTopicsRuntimeInfoAsync` and `GetSubscriptionsRuntimeInfoAsync` to `ManagementClient` to allow retrieval of batched entity runtime information. [PR 10261](https://github.com/Azure/azure-sdk-for-net/pull/10261)

sdk/servicebus/Microsoft.Azure.ServiceBus/src/Microsoft.Azure.ServiceBus.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <AssemblyTitle>Azure ServiceBus SDK</AssemblyTitle>
     <Description>This is the next generation Azure Service Bus .NET Standard client library that focuses on queues &amp; topics. For more information about Service Bus, see https://azure.microsoft.com/en-us/services/service-bus/</Description>
-    <Version>4.1.4</Version>
+    <Version>5.0.0</Version>
     <PackageTags>Microsoft;Azure;Service Bus;ServiceBus;.NET;AMQP;IoT;Queue;Topic</PackageTags>
     <TargetFrameworks>$(RequiredTargetFrameworks)</TargetFrameworks>
     <NoWarn>$(NoWarn);CS1591;CS1573;NU5125</NoWarn>