feat: Add half-yearly asset maintenance periodicity. (#37006)

diff --git a/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py b/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py
index 641d35f..125d4bf 100644
--- a/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py
+++ b/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py
@@ -79,14 +79,16 @@
 		next_due_date = add_days(start_date, 7)
 	if periodicity == "Monthly":
 		next_due_date = add_months(start_date, 1)
+	if periodicity == "Quarterly":
+		next_due_date = add_months(start_date, 3)
+	if periodicity == "Half-yearly":
+		next_due_date = add_months(start_date, 6)
 	if periodicity == "Yearly":
 		next_due_date = add_years(start_date, 1)
 	if periodicity == "2 Yearly":
 		next_due_date = add_years(start_date, 2)
 	if periodicity == "3 Yearly":
 		next_due_date = add_years(start_date, 3)
-	if periodicity == "Quarterly":
-		next_due_date = add_months(start_date, 3)
 	if end_date and (
 		(start_date and start_date >= end_date)
 		or (last_completion_date and last_completion_date >= end_date)
diff --git a/erpnext/assets/doctype/asset_maintenance_task/asset_maintenance_task.json b/erpnext/assets/doctype/asset_maintenance_task/asset_maintenance_task.json
index b7cb23e..80d90c6 100644
--- a/erpnext/assets/doctype/asset_maintenance_task/asset_maintenance_task.json
+++ b/erpnext/assets/doctype/asset_maintenance_task/asset_maintenance_task.json
@@ -71,7 +71,7 @@
    "fieldtype": "Select",
    "in_list_view": 1,
    "label": "Periodicity",
-   "options": "\nDaily\nWeekly\nMonthly\nQuarterly\nYearly\n2 Yearly\n3 Yearly",
+   "options": "\nDaily\nWeekly\nMonthly\nQuarterly\nHalf-yearly\nYearly\n2 Yearly\n3 Yearly",
    "reqd": 1
   },
   {
@@ -153,4 +153,4 @@
  "quick_entry": 1,
  "sort_field": "modified",
  "sort_order": "DESC"
-}
\ No newline at end of file
+}