♻️(models) allow null titles on documents

We want to make it as fast as possible to create a new document.
We should not have any modal asking the title before creating the
document but rather show an "untitle document" title and let the
owner set it on the already created document.

src/backend/core/migrations/0005_remove_document_is_public_alter_document_link_reach_and_more.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.1 on 2024-09-09 17:49
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0004_migrate_is_public_to_link_reach'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='document',
+            name='title',
+            field=models.CharField(blank=True, max_length=255, null=True, verbose_name='title'),
+        ),
+    ]