[doc] move Multilingual Search from user to admin docs

settings.yml snippets have no place in the user docs.

docs/admin/engines/settings.rst

@@ -353,6 +353,30 @@ engine is shown.  Most of the options have a default value or even are optional.
    engines, and so won't be described here.
 
 
+Example: Multilingual Search
+----------------------------
+
+SearXNG does not support true multilingual search.
+You have to use the language prefix in your search query when searching in a different language.
+
+But there is a workaround:
+By adding a new search engine with a different language, SearXNG will search in your default and other language.
+
+Example configuration in settings.yml for a German and English speaker:
+ .. code-block:: yaml
+
+    search:
+        default_lang : "de"
+        ...
+
+    engines:
+      - name : google english
+        engine : google
+        language : en
+        ...
+
+When searching, the default google engine will return German results and "google english" will return English results.
+
 .. _settings use_default_settings:
 
 use_default_settings

docs/user/search_syntax.rst

@@ -37,27 +37,3 @@ Image search:
 Custom language in wikipedia:
 
 - :search:`:hu !wp hackerspace <?q=%3Ahu%20%21wp%20hackerspace>`
-
-Multilingual Search
-===================
-
-SearXNG does not support true multilingual search.
-You have to use the language prefix in your search query when searching in a different language.
-
-But there is a workaround:
-By adding a new search engine with a different language, SearXNG will search in your default and other language.
-
-Example configuration in settings.yml for a German and English speaker:
- .. code-block:: yaml
-
-    search:
-        default_lang : "de"
-        ...
-
-    engines:
-      - name : google english
-        engine : google
-        language : en
-        ...
-
-When searching, the default google engine will return German results and "google english" will return English results.