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'),
+        ),
+    ]

judge/models/contest.py

@@ -72,7 +72,8 @@ class Contest(models.Model):
     problems = models.ManyToManyField(Problem, verbose_name=_('problems'), through='ContestProblem')
     start_time = models.DateTimeField(verbose_name=_('start time'), db_index=True)
     end_time = models.DateTimeField(verbose_name=_('end time'), db_index=True)
-    time_limit = models.DurationField(verbose_name=_('time limit'), blank=True, null=True)
+    time_limit = models.DurationField(verbose_name=_('time limit'), blank=True, null=True,
+        help_text=_('Format hh:mm:ss. For example, if you want a 2-hour contest, enter 02:00:00'))
     is_visible = models.BooleanField(verbose_name=_('publicly visible'), default=False,
                                      help_text=_('Should be set even for organization-private contests, where it '
                                                  'determines whether the contest is visible to members of the '