Add an help text to gauge

ram/metadata/migrations/0019_alter_scale_gauge.py

@@ -0,0 +1,22 @@
+# Generated by Django 5.1.2 on 2024-11-04 21:32
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("metadata", "0018_alter_decoder_options_alter_scale_options_and_more"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="scale",
+            name="gauge",
+            field=models.CharField(
+                blank=True,
+                help_text="Distance between real tracks. Please specify the unit (mm, in, ...)",
+                max_length=16,
+            ),
+        ),
+    ]