Add help text to contest time limit

judge/migrations/0122_auto_20220425_1202.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.25 on 2022-04-25 05:02
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('judge', '0121_auto_20220415_0135'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='contest',
+            name='time_limit',
+            field=models.DurationField(blank=True, help_text='Format hh:mm:ss. For example, if you want a 2-hour contest, enter 02:00:00', null=True, verbose_name='time limit'),
+        ),
+    ]