Update RELEASE_NOTES.md for 0.5.0 release (#122)

* Update RELEASE_NOTES.md for 0.5.0 release

* Remove trailing whitespaces

* Fix RELEASE_NOTES

RELEASE_NOTES.md

@@ -1,3 +1,101 @@
+## [0.5.0] / 9 October 2022
+* [Update Akka.NET from 1.4.41 to 1.4.43](https://github.com/akkadotnet/akka.net/releases/tag/1.4.43)
+* [Add full options support to Akka.Persistence.SqlServer.Hosting](https://github.com/akkadotnet/Akka.Hosting/pull/107)
+* [Improved Akka.Remote.Hosting implementation](https://github.com/akkadotnet/Akka.Hosting/pull/108)
+* [Add a standardized option code pattern for Akka.Hosting developer](https://github.com/akkadotnet/Akka.Hosting/pull/110)
+* [Add Akka.Hosting.TestKit module for unit testing projects using Akka.Hosting](https://github.com/akkadotnet/Akka.Hosting/pull/102)
+
+**Add full options support to Akka.Persistence.SqlServer.Hosting**
+
+You can now use an option class in Akka.Persistence.SqlServer.Hosting to replace HOCON configuration fully.
+
+**Add Akka.Hosting.TestKit module**
+
+The biggest difference between _Akka.Hosting.TestKit_ and _Akka.TestKit_ is that, since the test is started asynchronously, the _TestKit_ properties and methods would not be available in the unit test class constructor anymore. Since the spec depends on Microsoft `HostBuilder`, configuration has to be broken down into steps. There are overridable methods that user can use to override virtually all of the setup process.
+
+These are steps of what overridable methods gets called. Not all of the methods needs to be overriden, at the minimum, if you do not need a custom hosting environment, you need to override the `ConfigureAkka` method.
+
+1. `ConfigureLogging(ILoggingBuilder)`
+
+   Add custom logger and filtering rules on the `HostBuilder` level.
+2. `ConfigureHostConfiguration(IConfigurationBuilder)` 
+
+   Inject any additional hosting environment configuration here, such as faking environment variables, in the `HostBuilder` level.
+3. `ConfigureAppConfiguration(HostBuilderContext, IConfigurationBuilder)`
+
+   Inject the application configuration.
+4. `ConfigureServices(HostBuilderContext, IServiceCollection)`
+
+   Add additional services needed by the test, such as mocked up services used inside the dependency injection.
+5. User defined HOCON configuration is injected by overriding the `Config` property, it is not passed as part of the constructor anymore.
+6. `ConfigureAkka(AkkaConfigurationBuilder, IServiceProvider)`
+
+   This is called inside `AddAkka`, use this to configure the `AkkaConfigurationBuilder`
+7. `BeforeTestStart()`
+
+   This method is called after the TestKit is initialized. Move all of the codes that used to belong in the constructor here.
+
+`Akka.Hosting.TestKit` extends `Akka.TestKit.TestKitBase` directly, all testing methods are available out of the box.
+All of the properties, such as `Sys` and `TestActor` will be available once the unit test class is invoked.
+
+**Add a standardized option code pattern for Akka.Hosting developer**
+
+This new feature is intended for Akka.Hosting module developer only, it is used to standardize how Akka.Hosting addresses a very common HOCON configuration pattern. This allows for a HOCON-less programmatic setup replacement for the HOCON path used to configure the HOCON property.
+
+The pattern:
+
+```text
+# This HOCON property references to a config block below
+akka.discovery.method = akka.discovery.config
+
+akka.discovery.config {
+    class = "Akka.Discovery.Config.ConfigServiceDiscovery, Akka.Discovery"
+    # other options goes here
+}
+```
+
+Example implementation:
+```csharp
+// The base class for the option, needs to implement the IHoconOption template interface
+public abstract class DiscoveryOptionBase : IHoconOption
+{ }
+
+// The actual option implementation
+public class ConfigOption : DiscoveryOptionBase
+{
+    // The path value in the akka.discovery.method property above
+    public string ConfigPath => "akka.discovery.config";
+
+    // The FQCN value in the akka.discovery.config.class property above
+    public Type Class => typeof(ConfigServiceDiscovery);
+
+    // Generate the same HOCON config as above
+    public void Apply(AkkaConfigurationBuilder builder, Setup setup = null)
+    {
+        // Modifies Akka.NET configuration either via HOCON or setup class
+        builder.AddHocon(
+            $"akka.discovery.method = {ConfigPath.ToHocon()}",
+            HoconAddMode.Prepend);
+        builder.AddHocon($"akka.discovery.config.class = {
+            Class.AssemblyQualifiedName.ToHocon()}",
+            HoconAddMode.Prepend);
+
+        // Rest of configuration goes here
+    }
+}
+
+// Akka.Hosting extension implementation
+public static AkkaConfigurationBuilder WithDiscovery(
+    this AkkaConfigurationBuilder builder,
+    DiscoveryOptionBase discOption)
+{
+    var setup = new DiscoverySetup();
+
+    // gets called here
+    discOption.Apply(builder, setup);
+}
+```
+
 ## [0.4.3] / 9 September 2022
 - [Update Akka.NET from 1.4.40 to 1.4.41](https://github.com/akkadotnet/akka.net/releases/tag/1.4.41)
 - [Cluster.Hosting: Add split-brain resolver support](https://github.com/akkadotnet/Akka.Hosting/pull/95)