rest_framework/api.html

Solution

Add setting.py file

 'rest_framework' 

The registration application

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'ap01.apps.Ap01Config',
    'rest_framework',
]