Add Akka.Hosting v1.5.51 health check documentation to README (#548)

- Added new section explaining persistence health checks
- Included code examples for both basic and ASP.NET Core configurations
- Updated table of contents
- Documents WithHealthCheck() method for journal and snapshot stores

Author: Aaronontheweb

README.md

@@ -12,6 +12,7 @@ If you're migrating from legacy `Akka.Persistence.Sql.Common` based plugins, you
 - [Akka.Persistence.Sql](#akkapersistencesql)
 - [Getting Started](#getting-started)
   * [The Easy Way, Using `Akka.Hosting`](#the-easy-way-using-akkahosting)
+    + [Health Checks (Akka.Hosting v1.5.51+)](#health-checks-akkahosting-v1551)
   * [The Classic Way, Using HOCON](#the-classic-way-using-hocon)
   * [Supported Database Providers](#supported-database-providers)
     + [Tested Database Providers](#tested-database-providers)
@@ -70,11 +71,70 @@ var host = new HostBuilder()
         });
     });
 ```
-If `dataOptions` are provided, you must supply enough information for linq2db to connect to the database. 
-This includes setting the connection string and provider name again, if necessary for your use case. 
-Please consult the Linq2Db documentation for more details on configuring a valid DataOptions object. 
+If `dataOptions` are provided, you must supply enough information for linq2db to connect to the database.
+This includes setting the connection string and provider name again, if necessary for your use case.
+Please consult the Linq2Db documentation for more details on configuring a valid DataOptions object.
 Note that `MappingSchema` and `RetryPolicy` will always be overridden by Akka.Persistence.Sql.
 
+### Health Checks (Akka.Hosting v1.5.51+)
+
+Starting with Akka.Hosting v1.5.51, you can add health checks for your persistence plugins to verify that journals and snapshot stores are properly initialized and accessible. These health checks integrate with `Microsoft.Extensions.Diagnostics.HealthChecks` and can be used with ASP.NET Core health check endpoints.
+
+To configure health checks, use the `.WithHealthCheck()` method when setting up your journal and snapshot store:
+
+```csharp
+var host = new HostBuilder()
+    .ConfigureServices((context, services) => {
+        services.AddAkka("my-system-name", (builder, provider) =>
+        {
+            builder
+                .WithSqlPersistence(
+                    connectionString: _myConnectionString,
+                    providerName: ProviderName.SqlServer2019,
+                    journal: j => j.WithHealthCheck(
+                        unHealthyStatus: HealthStatus.Degraded,
+                        name: "sql-journal"),
+                    snapshot: s => s.WithHealthCheck(
+                        unHealthyStatus: HealthStatus.Degraded,
+                        name: "sql-snapshot"));
+        });
+    });
+```
+
+The health checks will automatically:
+- Verify the persistence plugin is configured correctly
+- Test connectivity to the underlying storage (database, cloud storage, etc.)
+- Report `Healthy` when the plugin is operational
+- Report `Degraded` or `Unhealthy` (configurable) when issues are detected
+
+Health checks are tagged with `akka`, `persistence`, and either `journal` or `snapshot-store` for filtering purposes.
+
+For ASP.NET Core applications, you can expose these health checks via an endpoint:
+
+```csharp
+var builder = WebApplication.CreateBuilder(args);
+
+// Add health checks service
+builder.Services.AddHealthChecks();
+
+builder.Services.AddAkka("my-system-name", (configBuilder, provider) =>
+{
+    configBuilder
+        .WithSqlPersistence(
+            connectionString: _myConnectionString,
+            providerName: ProviderName.SqlServer2019,
+            journal: j => j.WithHealthCheck(),
+            snapshot: s => s.WithHealthCheck());
+});
+
+var app = builder.Build();
+
+// Map health check endpoint
+app.MapHealthChecks("/healthz");
+
+app.Run();
+```
+
 ## The Classic Way, Using HOCON
 
 These are the minimum HOCON configuration you need to start using Akka.Persistence.Sql: