[fix] various issues in the documentation

Closes: https://github.com/searxng/searxng/issues/4370
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

docs/admin/settings/index.rst

@@ -13,7 +13,7 @@ Settings
    :maxdepth: 2
 
    settings
-   settings_engine
+   settings_engines
    settings_brand
    settings_general
    settings_search

docs/admin/settings/settings_engines.rst

@@ -1,14 +1,30 @@
-.. _settings engine:
+.. _settings engines:
 
-===========
-``engine:``
-===========
+============
+``engines:``
+============
 
 .. sidebar:: Further reading ..
 
    - :ref:`configured engines`
    - :ref:`engines-dev`
 
+
+In the section ``engines:`` is a list of the engines that are to be made
+available in the instance.  Each list entry is in turn a key/value mapping.
+
+.. code:: yaml
+
+   engines:
+
+     - name: dummy.online
+       engine: dummy
+       ..
+     - name: dummy.offline
+       engine: dummy-offline
+       ..
+     ..
+
 In the code example below a *full fledged* example of a YAML setup from a dummy
 engine is shown.  Most of the options have a default value or even are optional.
 
@@ -19,7 +35,7 @@ engine is shown.  Most of the options have a default value or even are optional.
 
 .. code:: yaml
 
-   - name: example engine
+   - name: example
      engine: example
      shortcut: demo
      base_url: 'https://{language}.example.com/'

docs/admin/settings/settings_outgoing.rst

@@ -43,7 +43,7 @@ Communication with search engines.
   Global timeout of the requests made to others engines in seconds.  A bigger
   timeout will allow to wait for answers from slow engines, but in consequence
   will slow SearXNG reactivity (the result page may take the time specified in the
-  timeout to load).  Can be override by ``timeout`` in the :ref:`settings engine`.
+  timeout to load).  Can be override by ``timeout`` in the :ref:`settings engines`.
 
 ``useragent_suffix`` :
   Suffix to the user-agent SearXNG uses to send requests to others engines.  If an
@@ -105,6 +105,6 @@ Communication with search engines.
 
 ``using_tor_proxy`` :
   Using tor proxy (``true``) or not (``false``) for all engines.  The default is
-  ``false`` and can be overwritten in the :ref:`settings engine`
+  ``false`` and can be overwritten in the :ref:`settings engines`