fix: add filenames for the code snippets

docs/how-to/add-model-and-api-endpoints.md

@@ -24,6 +24,8 @@ Let's start!
 
 ### Add the model in django
 
+Add the following to app/core/models.py
+
 ```python
 class RecurringEvent(AbstractBaseModel):
     """
@@ -75,6 +77,10 @@ Since we overrode the `__str__` function, we need to write a test for it.
 
    Fixtures are reusable code that can be used in multiple tests by declaring them as parameters of the test case. In this example, we show both defining a fixture (recurring_event) and using another fixture (project).
 
+   Note: The conftest file is meant to hold shared test fixtures, among other things. The fixtures have directory scope.
+
+   Add the following to app/core/tests/conftest.py
+
    ```python
    @pytest.fixture
    def recurring_event(project):
@@ -93,6 +99,8 @@ Since we overrode the `__str__` function, we need to write a test for it.
 
    Here's a basic test to see that the model stores its name.
 
+   Add the following to app/core/tests/test_models.py
+
    ```python
    def test_recurring_event(recurring_event):
        assert str(recurring_event) == "Test Recurring Event"