[doc] introduce about.language and sort engines by it

docs/admin/engines/configured_engines.rst

@@ -43,6 +43,9 @@ Explanation of the :ref:`general engine configuration` shown in the table
         - ``!{{mod.shortcut}}``
         - {{mod.__name__}}
         - {{(mod.disabled and "y") or ""}}
+          {%- if mod.about and  mod.about.language %}
+          ({{mod.about.language | upper}})
+          {%- endif %}
         - {{mod.timeout}}
         - {{mod.weight or 1 }}
         {% if mod.engine_type == 'online' %}

docs/conf.py

@@ -50,7 +50,11 @@ jinja_contexts = {
     },
 }
 jinja_filters = {
-    'sort_engines': lambda engines: sorted(engines, key=lambda engine: (engine[1].disabled, engine[0]))
+    'sort_engines':
+    lambda engines: sorted(
+        engines,
+        key=lambda engine: (engine[1].disabled, engine[1].about.get('language', ''), engine[0])
+    )
 }
 
 # usage::   lorem :patch:`f373169` ipsum