Fixed #166 -- Highlight the significance of the double underscore syn…

…tax.

django_models/README.md

@@ -141,6 +141,8 @@ What about `def publish(self):`? It is exactly our `publish` method we were talk
 
 Methods very often `return` something. There is an example of that in the `__str__` method. In this scenario, when we call `__str__()` we will get a text (**string**) with a Post title.
 
+> **Note** Yes, there are two undescore characters (`_`) on each side. Those are used frequently in Python and sometimes we also call them "dunder" (short for "double-underscore").
+
 If something is still not clear about models, feel free to ask your coach! We know it is very complicated, especially when you learn what objects and functions are at the same time. But hopefully it looks slightly less magic for you now!
 
 ### Create tables for models in your database

django_orm/README.md

@@ -99,6 +99,8 @@ Or maybe we want to see all the posts that contain a word 'title' in the `title`
     >>> Post.objects.filter(title__contains='title')
     [<Post: Sample title>, <Post: 4th title of post>]
 
+> **Note** There are two underscore characters (`_`) between `title` and `contains`. Django's ORM uses this syntax to separate field names ("title") and operations or filters ("contains").
+
 You can also get a list of all published posts. We do it by filtering all the posts that have `published_date`:
 
     >>> Post.objects.filter(published_date__isnull=False)