Correct admin url prepend conf (#796)

The configuration for prepending a string to the admin url was
unintentionally removed by a typo, this adds it back in.

Author: whytheplatypus

hhs_oauth_server/settings/base.py

@@ -438,7 +438,8 @@
 
 LOGOUT_REDIRECT_URL = '/'
 
-# Move Admin to a variable url location ADMIN_PREPEND_URL = env('DJANGO_ADMIN_PREPEND_URL', '')
+# Move Admin to a variable url location
+ADMIN_PREPEND_URL = env('DJANGO_ADMIN_PREPEND_URL', '')
 
 ALLOW_END_USER_EXTERNAL_AUTH = "B"
 EXTERNAL_AUTH_NAME = 'MyMedicare.gov'