Store the BBB link in the Pool model

apps/participation/migrations/0012_pool_bbb_code.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.0.11 on 2021-01-21 16:47
+
+import django.core.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('participation', '0011_note'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='pool',
+            name='bbb_code',
+            field=models.CharField(blank=True, default='', help_text='The code of the form xxx-xxx-xxx at the end of the BBB link.', max_length=11, validators=[django.core.validators.RegexValidator('[a-z]{3}-[a-z]{3}-[a-z]{3}')], verbose_name='BigBlueButton code'),
+        ),
+    ]