fix typo

Author: fsbraun

docs/source/tutorial/builtin_components.rst

@@ -271,7 +271,7 @@ on the number of users it may take some time.
 Limitations of built-in components
 ==================================
 
-Built-oin components are a powerful tool for content editors, especially if they are used to
+Built-in components are a powerful tool for content editors, especially if they are used to
 using the Bootstrap CSS framework. Those components are both portable to other frameworks
 and extensible (see :ref:`how-to-extend-frontend-plugins`) But they have some limitations:
 

docs/source/tutorial/custom_components.rst

@@ -197,6 +197,6 @@ By following the steps outlined above, you can:
 
 .. note::
 
-    Components will create migrations since they use proxy models which are necessary, for
-    example, to manage permissions. Those migrations will be added to the app containing
-    the ``cms_component.py`` file.
+    Components will create migrations since they use proxy models of ``djangocms-frontend``'s
+    ``FrontendUIItem`` model which are necessary, for example, to manage permissions.
+    Those migrations will be added to the app containing the ``cms_component.py`` file.