manual: rename users.extraUsers to users.users

Is called like this since 14321ae, but
docs were still using the old option in some cases.

Reported-By: Cedric Shahabi <cedric.shahabi@gmail.com>
(cherry picked from commit 6cabce9abd916f219c1c003719f2e8ba547654c3)

nixos/doc/manual/administration/imperative-containers.xml

@@ -27,7 +27,7 @@
 <screen>
 # nixos-container create foo --config '
   services.openssh.enable = true;
-  users.extraUsers.root.openssh.authorizedKeys.keys = ["ssh-dss AAAAB3N…"];
+  users.users.root.openssh.authorizedKeys.keys = ["ssh-dss AAAAB3N…"];
 '
 </screen>
  </para>

nixos/doc/manual/configuration/network-manager.xml

@@ -19,7 +19,7 @@ networking.networkmanager.enable = true;
   All users that should have permission to change network settings must belong
   to the <code>networkmanager</code> group:
 <programlisting>
-users.extraUsers.youruser.extraGroups = [ "networkmanager" ];
+users.users.youruser.extraGroups = [ "networkmanager" ];
 </programlisting>
  </para>
 

nixos/doc/manual/configuration/ssh.xml

@@ -20,7 +20,7 @@ services.openssh.enable = true;
   follows:
 <!-- FIXME: this might not work if the user is unmanaged. -->
 <programlisting>
-users.extraUsers.alice.openssh.authorizedKeys.keys =
+users.users.alice.openssh.authorizedKeys.keys =
   [ "ssh-dss AAAAB3NzaC1kc3MAAACBAPIkGWVEt4..." ];
 </programlisting>
  </para>

nixos/doc/manual/installation/changing-config.xml

@@ -66,7 +66,7 @@ $ ./result/bin/run-*-vm
   <literal>mutableUsers = false</literal>. Another way is to temporarily add
   the following to your configuration:
 <screen>
-users.extraUsers.your-user.initialPassword = "test"  
+users.users.your-user.initialPassword = "test"  
 </screen>
   <emphasis>Important:</emphasis> delete the $hostname.qcow2 file if you have
   started the virtual machine at least once without the right users, otherwise

nixos/doc/manual/installation/installing-from-other-distro.xml

@@ -210,7 +210,7 @@ $ sudo groupdel nixbld</screen>
     or to lock the account with <literal>sudo passwd -l root</literal> if you
     use <literal>sudo</literal>)
    </para>
-<programlisting>users.extraUsers.root.initialHashedPassword = "";</programlisting>
+<programlisting>users.users.root.initialHashedPassword = "";</programlisting>
   </listitem>
   <listitem>
    <para>