Rename 'salvage value' to 'replacement cost'

This more accurately reflects historical use of the field, and what the insurers actually want. Ref #439

assets/migrations/0025_rename_salvage_value_asset_replacement_cost.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2022-05-26 09:22
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('assets', '0024_alter_asset_salvage_value'),
+    ]
+
+    operations = [
+        migrations.RenameField(
+            model_name='asset',
+            old_name='salvage_value',
+            new_name='replacement_cost',
+        ),
+    ]