Fix NETSDK1228 error: use Aspire.AppHost.Sdk instead of deprecated workload, update README

Co-authored-by: kamilbaczek <74410956+kamilbaczek@users.noreply.github.com>

Author: Copilot

Chapter-3-microservice-extraction/Fitnet.Contracts/Src/Fitnet.Contracts.AppHost/Fitnet.Contracts.AppHost.csproj

@@ -1,8 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <Sdk Name="Aspire.AppHost.Sdk" Version="13.0.0" />
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <IsAspireHost>true</IsAspireHost>
   </PropertyGroup>
 
   <ItemGroup>

Chapter-3-microservice-extraction/Fitnet/Src/Fitnet.AppHost/Fitnet.AppHost.csproj

@@ -1,8 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <Sdk Name="Aspire.AppHost.Sdk" Version="13.0.0" />
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <IsAspireHost>true</IsAspireHost>
   </PropertyGroup>
 
   <ItemGroup>

Chapter-3-microservice-extraction/README.adoc

@@ -162,23 +162,39 @@ That's it! You should now be able to run the application using either one of the
 
 === Run with .NET Aspire
 
-The Fitnet application uses .NET Aspire for local development.
+The Fitnet application uses .NET Aspire for local development orchestration.
 
-To run the application locally using Aspire, follow these steps:
+==== Run Fitnet Modular Monolith
 
 1. **Ensure Docker is running** on your machine.
-2. **Navigate to the AppHost directory:**
+2. **Navigate to the Fitnet AppHost directory:**
 [source,shell]
 ----
-cd Fitnet.AppHost
+cd Fitnet/Src/Fitnet.AppHost
 ----
 3. **Run the AppHost project:**
 [source,shell]
 ----
 dotnet run
 ----
 
-The Aspire Dashboard will open automatically, showing all services, resources, and logs.
+The Aspire Dashboard will open automatically, showing the Fitnet modular monolith and PostgreSQL database.
+
+==== Run Fitnet.Contracts Microservice
+
+1. **Ensure Docker is running** on your machine.
+2. **Navigate to the Contracts AppHost directory:**
+[source,shell]
+----
+cd Fitnet.Contracts/Src/Fitnet.Contracts.AppHost
+----
+3. **Run the AppHost project:**
+[source,shell]
+----
+dotnet run
+----
+
+The Aspire Dashboard will open automatically, showing the Fitnet.Contracts microservice, PostgreSQL database, and RabbitMQ message broker.
 
 === Building and debugging code in Rider IDE