Apply suggestions from code review

Co-authored-by: Adrián Chaves <adrian@chaves.io>

docs/topics/settings.rst

@@ -81,7 +81,7 @@ to do so is by setting their :attr:`~scrapy.Spider.custom_settings` attribute:
             "SOME_SETTING": "some value",
         }
 
-It's often better to provide a :meth:`~scrapy.Spider.update_settings` instead,
+It's often better to implement :meth:`~scrapy.Spider.update_settings` instead,
 and settings set there should use the "spider" priority explicitly:
 
 .. code-block:: python
@@ -94,8 +94,8 @@ and settings set there should use the "spider" priority explicitly:
 
         @classmethod
         def update_settings(cls, settings):
-            settings.set("SOME_SETTING", "some value", priority="spider")
             super().update_settings(settings)
+            settings.set("SOME_SETTING", "some value", priority="spider")
 
 3. Project settings module
 --------------------------

docs/topics/spiders.rst

@@ -162,7 +162,7 @@ scrapy.Spider
        settings, spider attributes or other factors and use setting priorities
        other than ``'spider'``. Also, it's easy to extend ``update_settings()``
        in a subclass by overriding it, while doing the same with
-       :attr:`~scrapy.Spider.custom_settings` is hard or impossible.
+       :attr:`~scrapy.Spider.custom_settings` can be hard.
 
        For example, suppose a spider needs to modify :setting:`FEEDS`:
 
@@ -182,8 +182,8 @@ scrapy.Spider
 
                @classmethod
                def update_settings(cls, settings):
-                   settings.setdefault("FEEDS", {}).update(cls.custom_feed)
                    super().update_settings(settings)
+                   settings.setdefault("FEEDS", {}).update(cls.custom_feed)
 
    .. method:: start_requests()