move two-factor items to system.

source/manual.rst

@@ -16,7 +16,6 @@ User Manual
    manual/dhcp
    manual/ipv6
    manual/nat
-   manual/two_factor
    manual/logging
    manual/aliases
    manual/vpnet

source/manual/howtos.rst

@@ -52,7 +52,6 @@ How-tos
    how-tos/sslvpn_client
    how-tos/sslvpn_s2s
    how-tos/tor
-   how-tos/two_factor
    how-tos/wireguard-client
    how-tos/wireguard-client-azire
    how-tos/wireguard-client-mullvad

source/system.rst

@@ -20,9 +20,21 @@ activities.
    manual/how-tos/user-local
    manual/how-tos/user-ldap
    manual/how-tos/user-radius
+   manual/two_factor
    manual/how-tos/cloud_backup
    manual/how-tos/multiwan
    manual/hacarp
    manual/settingsmenu
    manual/certificates
    manual/diagnostics
+
+
+---------------
+Setup guides
+---------------
+
+.. toctree::
+   :maxdepth: 2
+   :titlesonly:
+
+   manual/how-tos/two_factor