[1.10.x] Fixed #26002 -- Explained ModelAdmin.get_search_results() example.

Backport of c9d0a0f7f4 from master

docs/ref/contrib/admin/index.txt

@@ -1395,7 +1395,7 @@ templates used by the :class:`ModelAdmin` views:
     implemented by your search method may introduce duplicates into the results,
     and return ``True`` in the second element of the return value.
 
-    For example, to enable search by integer field, you could use::
+    For example, to search by ``name`` and ``age``, you could use::
 
         class PersonAdmin(admin.ModelAdmin):
             list_display = ('name', 'age')
@@ -1411,6 +1411,11 @@ templates used by the :class:`ModelAdmin` views:
                     queryset |= self.model.objects.filter(age=search_term_as_int)
                 return queryset, use_distinct
 
+    This implementation is more efficient than ``search_fields =
+    ('name', '=age')`` which results in a string comparison for the numeric
+    field, for example ``... OR UPPER("polls_choice"."votes"::text) = UPPER('4')``
+    on PostgreSQL.
+
 .. method:: ModelAdmin.save_related(request, form, formsets, change)
 
     The ``save_related`` method is given the ``HttpRequest``, the parent