add affiliate journal description field

fixes #264

scipost_django/affiliates/migrations/0013_affiliatejournal_description.py

+# Generated by Django 4.2.10 on 2024-05-23 08:22
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("affiliates", "0012_affiliatejournal_logo_svg"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="affiliatejournal",
+            name="description",
+            field=models.TextField(blank=True),
+        ),
+    ]

scipost_django/affiliates/models/journal.py

@@ -23,6 +23,7 @@ class AffiliateJournal(models.Model):
     )
 
     name = models.CharField(max_length=256)
+    description = models.TextField(blank=True)
 
     short_name = models.CharField(max_length=256, default="")