added checksums for archived documents.

src/documents/migrations/1005_checksums.py

@@ -0,0 +1,23 @@
+# Generated by Django 3.1.3 on 2020-11-29 00:48
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('documents', '1004_sanity_check_schedule'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='document',
+            name='archive_checksum',
+            field=models.CharField(blank=True, editable=False, help_text='The checksum of the archived document.', max_length=32, null=True),
+        ),
+        migrations.AlterField(
+            model_name='document',
+            name='checksum',
+            field=models.CharField(editable=False, help_text='The checksum of the original document.', max_length=32, unique=True),
+        ),
+    ]