Fixup notes about building and testing this project.

CONTRIBUTING.md

@@ -78,25 +78,37 @@ ask the core team for their opinion on the [RabbitMQ users mailing list][rmq-use
 
 ### Building Source
 
-To build the projects first, clone the repository. Make sure you clone the
-repository and its submodules:
-
 It is good practice to make sure you can build the project before making any
-changes to confirm that your development environment is set
-up correctly. Verifying that the tests pass is also a good practice (see
+changes to confirm that your development environment is set up correctly.
+Verifying that the tests pass is also a good practice (see
 [RUNNING_TESTS.md](/RUNNING_TESTS.md)).
 
 All together, this looks like:
 
+* Linux
+
 ```shell
 git clone --recurse-submodules https://github.com/rabbitmq/rabbitmq-dotnet-client
 cd rabbitmq-dotnet-client
-dotnet build ./Build.csproj
-./.ci/ubuntu/gha-setup.sh   # On any Linux distribution with Docker installed
-./.ci/windows/gha-setup.ps1 # On Windows
+
+# On any Linux distribution with Docker installed
+./.ci/ubuntu/gha-setup.sh toxiproxy pull
+
+make build
 make test
 ```
 
+* Windows
+
+Note that this will _NOT_ run toxiproxy tests.
+
+```powershell
+git clone --recurse-submodules https://github.com/rabbitmq/rabbitmq-dotnet-client
+cd rabbitmq-dotnet-client
+./.ci/windows/gha-setup.ps1 # On Windows. Note that this installs RabbitMQ
+.\build.ps1 -RunTests:$true
+```
+
 ### Running Tests
 
 See [RUNNING_TESTS.md](/RUNNING_TESTS.md).