Add a note about which installation variant to use and when.

Signed-off-by: Volker Theile <votdev@gmx.de>

installation/index.rst

@@ -4,33 +4,39 @@ Installation
 ############
 
 Before you begin:
-	- Check if your hardware is supported on the system :doc:`requirements
-	  page </prerequisites>`.
+    - Check if your hardware is supported on the system :doc:`requirements
+      page </prerequisites>`.
 
 Installation variants:
-	Choose your installation variant and follow the instructions.
+    Choose your installation variant and follow the instructions.
 
-	* :doc:`Dedicated drive </installation/via_iso>` - Advised method via ISO image. This runs OMV from its own drive.
-	* :doc:`USB flash drive </installation/on_usb>` - This runs |omv| from a USB flash drive.
-	* :doc:`Debian Operating System </installation/on_debian>` - Use an existing Debian OS installation for |omv|.
-	* `Debian Operating System via debootstrap <https://forum.openmediavault.org/index.php/Thread/12070-GUIDE-DEBOOTSTRAP-Installing-Debian-into-a-folder-in-a-running-system/>`_. Use this as a last resort in case the installer does not recognize a specific essential hardware component like hard disk (NVME) or a network card that needs a higher kernel (backport).
-	* :doc:`SD card </installation/via_image>` - This runs |omv| from a SD card.
+    .. note::
+        Choose the :doc:`Dedicated drive </installation/via_iso>` variant if
+        you like to install |omv| from scratch on x86/AMD64 hardware. For SBC
+        systems based on the ARM32/64 architecture use the :doc:`Debian Operating System </installation/on_debian>`
+        variant.
+
+    * :doc:`Dedicated drive </installation/via_iso>` - Advised method via ISO image. This runs OMV from its own drive.
+    * :doc:`USB flash drive </installation/on_usb>` - This runs |omv| from a USB flash drive.
+    * :doc:`Debian Operating System </installation/on_debian>` - Use an existing Debian OS installation for |omv|.
+    * `Debian Operating System via debootstrap <https://forum.openmediavault.org/index.php/Thread/12070-GUIDE-DEBOOTSTRAP-Installing-Debian-into-a-folder-in-a-running-system/>`_. Use this as a last resort in case the installer does not recognize a specific essential hardware component like hard disk (NVME) or a network card that needs a higher kernel (backport).
+    * :doc:`SD card </installation/via_image>` - This runs |omv| from a SD card.
 
 First time use:
-	If you have a screen attached, KVM or IMPI console the login screen will
-	display the current IP address assigned for the |webui|. Open your browser
-	and type that IP address. The default |webui| login credential is
-	``admin:openmediavault``, the ``root`` password is the one you setup during
-	installation.
-
-	For ARM images the root password is the same as admin password.
-
-.. note::
-   |omv| will enable SSH access for the user ``root`` by default to be
-   able to access a headless system in case of a broken installation or
-   other maintenance situations. You should disable this behaviour in the
-   ``Services | SSH`` page for security reasons after installation.
-
-   To still get ``root`` access you need to create a non-privileged user
-   and add them to the ``ssh`` and ``sudo`` groups. After that you can
-   SSH into the system with this non-privileged user and run ``sudo su``.
+    If you have a screen attached, KVM or IMPI console the login screen will
+    display the current IP address assigned for the |webui|. Open your browser
+    and type that IP address. The default |webui| login credential is
+    ``admin:openmediavault``, the ``root`` password is the one you setup during
+    installation.
+
+    For ARM images the root password is the same as admin password.
+
+    .. note::
+       |omv| will enable SSH access for the user ``root`` by default to be
+       able to access a headless system in case of a broken installation or
+       other maintenance situations. You should disable this behaviour in the
+       ``Services | SSH`` page for security reasons after installation.
+
+       To still get ``root`` access you need to create a non-privileged user
+       and add them to the ``ssh`` and ``sudo`` groups. After that you can
+       SSH into the system with this non-privileged user and run ``sudo su``.