docs: replace use of # by $ sudo

The hope is that this makes it more obvious that these commands should
be run as the root user.

docs/installation.adoc

@@ -124,21 +124,21 @@ deployed through NixOps.
 
 To make the NixOS module available for use you must `import` it into
 your system configuration. This is most conveniently done by adding a
-Home Manager channel. For example, if you are following Nixpkgs master
-or an unstable channel, you can run
+Home Manager channel to the root user. For example, if you are
+following Nixpkgs master or an unstable channel, you can run
 
 [source,console]
 ----
-# nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
-# nix-channel --update
+$ sudo nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
+$ sudo nix-channel --update
 ----
 
 and if you follow a Nixpkgs version 22.05 channel, you can run
 
 [source,console]
 ----
-# nix-channel --add https://github.com/nix-community/home-manager/archive/release-22.05.tar.gz home-manager
-# nix-channel --update
+$ sudo nix-channel --add https://github.com/nix-community/home-manager/archive/release-22.05.tar.gz home-manager
+$ sudo nix-channel --update
 ----
 
 It is then possible to add
@@ -161,7 +161,7 @@ home-manager.users.eve = { pkgs, ... }: {
 };
 ----
 
-and after a `nixos-rebuild switch` the user eve's environment should
+and after a `sudo nixos-rebuild switch` the user eve's environment should
 include a basic Bash configuration and the packages atool and httpie.
 
 [NOTE]

docs/manual.xml

@@ -24,7 +24,7 @@
   </para>
   <note>
    <para>
-    Commands prefixed with <literal>#</literal> have to be run as root, either
+    Commands prefixed with <literal>$ sudo</literal> have to be run as root, either
     requiring to login as root user or temporarily switching to it using
     <literal>sudo</literal> for example.
    </para>