Add letter in pool display

Signed-off-by: Emmy D'Anello <emmy.danello@animath.fr>

participation/migrations/0004_alter_pool_options_pool_letter.py

@@ -0,0 +1,30 @@
+# Generated by Django 4.1.7 on 2023-03-31 15:17
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("participation", "0003_alter_team_trigram"),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name="pool",
+            options={
+                "ordering": ("round", "letter"),
+                "verbose_name": "pool",
+                "verbose_name_plural": "pools",
+            },
+        ),
+        migrations.AddField(
+            model_name="pool",
+            name="letter",
+            field=models.PositiveSmallIntegerField(
+                choices=[(1, "A"), (2, "B"), (3, "C"), (4, "D")],
+                default=1,
+                verbose_name="letter",
+            ),
+            preserve_default=False,
+        ),
+    ]