Move core user docs back to appropriate sections

Requested by: https://github.com/QubesOS/qubes-doc/pull/823#issuecomment-496316322
Related to: QubesOS/qubes-issues#4693

user/advanced-configuration/kde.md

@@ -0,0 +1,88 @@
+---
+layout: doc
+title: KDE
+permalink: /doc/kde/
+redirect_from: /en/doc/kde/
+---
+
+Using KDE in dom0
+=================
+
+Installation
+------------
+
+Prior to R3.2, KDE was the default desktop environment in Qubes. Beginning with
+R3.2, however, [XFCE is the new default desktop environment](/doc/releases/3.2/release-notes/). Nonetheless, it is
+still possible to install KDE by issuing this command in dom0:
+
+    $ sudo qubes-dom0-update @kde-desktop-qubes
+
+You can also change your default login manager (lightdm) to the new KDE default: sddm
+
+ * first you need to edit the `/etc/sddm.conf` to make sure if the custom X parameter is set according to Qubes needs:
+
+~~~
+   [XDisplay]
+   ServerArguments=-nolisten tcp -background none
+~~~
+
+ * disable the lightdm service:
+
+~~~  
+   $ sudo systemctl disable lightdm
+~~~  
+
+ * enable the sddm service:
+
+~~~
+    $ sudo systemctl enable sddm
+~~~
+
+ * reboot
+
+If you encounter performance issues with KDE, try switching back to LightDM.
+
+Window Management
+-----------------
+
+You can set each window's position and size like this:
+
+~~~
+Right click title bar --> More actions --> Special window settings...
+
+  Window matching tab
+    Window class (application): Exact Match: <vm_name>
+    Window title: Substring Match: <partial or full program name>
+
+  Size & Position tab
+    [x] Position: Apply Initially: x,y
+    [x] Size: Apply Initially: x,y
+~~~
+
+You can also use `kstart` to control virtual desktop placement like this:
+
+~~~
+  kstart --desktop 3 --windowclass <vm_name> -q --tray -a <vm_name> '<run_program_command>'
+~~~
+
+(Replace "3" with whichever virtual desktop you want the window to be
+on.)
+
+This can be useful for creating a simple shell script which will set up your
+workspace the way you like.
+
+Removal
+------------
+
+If you decide to remove KDE do **not** use `dnf remove @kde-desktop-qubes`. You will almost certainly break your system.
+
+The safest way to remove (most of) KDE is:
+~~~
+sudo dnf remove kdelibs,plasma-workspace
+~~~
+
+
+Mailing List Threads
+--------------------
+
+ * [Nalu's KDE customization thread](https://groups.google.com/d/topic/qubes-users/KhfzF19NG1s/discussion)