Combine theming pages into one

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

admin_manual/configuration_server/theming.rst

@@ -2,7 +2,21 @@
 Theming
 =======
 
-In the administrative settings you can modify the appearance of Nextcloud:
+Nextcloud has two ways of theming. There is a theming app that provides a web
+UI to set up theming. The second option allows to overwrite most of the files
+but a customized theme needs to be created and maintained. For more information on
+this check out the `developers documentation <../../developer_manual/core/theming.html>`_.
+
+We recommend to use the theming app, because the Nextcloud team maintains this
+and verifies that all adjustments to the server work with the theming. It
+covers also most use cases like replacing the name, logos and colors.
+
+Theming app
+===========
+
+Check in the apps management that the theming app is enabled. Then the
+administrator settings show a section where you can modify the appearance of
+your Nextcloud:
 
 * Name 
 * Web Address 

admin_manual/operations/index.rst

@@ -10,5 +10,4 @@ creating a custom theme for your Nextcloud server.
    
    considerations_on_monitoring
    scaling_multiple_machines.rst
-   theming.rst
 

admin_manual/operations/theming.rst

@@ -1,12 +0,0 @@
-=================
-Theming Nextcloud
-=================
-
-.. toctree::
-    :maxdepth: 2
-    :hidden:
-
-
-Theming can be done very easily using the shipped `theming app <../configuration_server/theming.html>`_, which is enabled by default.
-
-For more individual theming options please head over to the `developers documentation <../../developer_manual/core/theming.html>`_.