migrations: Add comment regarding order of migrations

Author: liquidpele

django_celery_beat/migrations/0006_periodictask_priority.py

@@ -7,6 +7,8 @@
 
 class Migration(migrations.Migration):
     dependencies = [
+        # depends on higher numbers due to a squashed migration
+        # that was later removed due to migration issues it caused
         ('django_celery_beat', '0005_add_solarschedule_events_choices'),
         ('django_celery_beat', '0006_auto_20180210_1226'),
         ('django_celery_beat', '0006_auto_20180322_0932'),