NixOS tutorials: add next steps

source/tutorials/module-system/module-system.md

@@ -1,3 +1,4 @@
+(module-system-deep-dive)=
 # Module system deep dive
 
 Or: *Wrapping the world in modules*

source/tutorials/nixos/building-and-running-docker-images.md

@@ -5,6 +5,7 @@ myst:
     "keywords": "Docker, containers, Nix, reproducible, build, tutorial"
 ---
 
+(nixos-docker-images)=
 # Building and running Docker images
 
 [Docker](https://www.docker.com/) is a set of tools and services used to build, manage and deploy containers.

source/tutorials/nixos/building-bootable-iso-image.md

@@ -1,3 +1,4 @@
+(bootable-iso-image)=
 # Building a bootable ISO image
 
 :::{note}

source/tutorials/nixos/integration-testing-using-virtual-machines.md

@@ -321,3 +321,9 @@ $ nix-build server-client-test.nix
   A good inspiration is [Matrix bridging with an IRC](https://github.com/NixOS/nixpkgs/blob/master/nixos/tests/matrix/appservice-irc.nix).
 
 <!-- TODO: move examples from https://nixos.wiki/wiki/NixOS_Testing_library to the NixOS manual and troubleshooting tips to nix.dev -->
+
+## Next steps
+
+- [](module-system-deep-dive)
+- [](bootable-iso-image)
+- [](nixos-docker-images)

source/tutorials/nixos/nixos-configuration-on-vm.md

@@ -6,20 +6,21 @@ One of the most important features of NixOS is the ability to configure the enti
 
 NixOS configurations can be used to test and use NixOS using a virtual machine, independent of an installation on a "bare metal" computer.
 
-:::{important}
-A NixOS configuration is a Nix language function following the [NixOS module](https://nixos.org/manual/nixos/stable/index.html#sec-writing-modules) convention.
-:::
-
 ## What will you learn?
 
 This tutorial serves as an introduction creating NixOS virtual machines.
-Virtual machines are a practical tool for debugging NixOS configurations.
+Virtual machines are a practical tool for experimenting with or debugging NixOS configurations.
 
 ## What do you need?
 
 - A working [Nix installation](https://nix.dev/manual/nix/2.18/installation/installation.html) on Linux, or [NixOS](https://nixos.org/manual/nixos/stable/index.html#sec-installation), with a graphical environment
 - Basic knowledge of the [Nix language](reading-nix-language)
 
+:::{important}
+A NixOS configuration is a Nix language function following the [NixOS module](https://nixos.org/manual/nixos/stable/index.html#sec-writing-modules) convention.
+For a thorough treatment of the module system, check the [](module-system-deep-dive) tutorial.
+:::
+
 ## Starting from a default NixOS configuration
 
 In this tutorial you will use a default configuration that is shipped with NixOS.
@@ -95,7 +96,7 @@ The default NixOS configuration without comments is:
 }
 ```
 
-To be able to log in add the following lines to the returned attribute set:
+To be able to log in, add the following lines to the returned attribute set:
 
 ```nix
   users.users.alice = {
@@ -242,3 +243,9 @@ rm nixos.qcow2
 - [Nix manual: `nix-build`](https://nix.dev/manual/nix/2.18/command-ref/nix-build.html).
 - [Nix manual: common command-line options](https://nix.dev/manual/nix/2.18/command-ref/opt-common.html).
 - [Nix manual: `NIX_PATH` environment variable](https://nix.dev/manual/nix/2.18/command-ref/env-common.html#env-NIX_PATH).
+
+## Next steps
+
+- [](module-system-deep-dive)
+- [](integration-testing-vms)
+- [](bootable-iso-image)