Add total registrations and revenue query documentation for ssmm

Care/Operations/totalregistrationsandrevenue_ssmm.md

@@ -0,0 +1,35 @@
+# Total Registrations and Revenue
+
+> Summary of total registration fee revenue
+
+## Purpose
+
+This query provides aggregate metrics for patient registrations, showing the total number of registrations and cumulative revenue from registration fees. It's useful for tracking registration volumes and revenue trends over time.
+
+## Parameters
+
+| Parameter | Type | Description | Example |
+|-----------|------|-------------|---------|
+| `date` | DATE | Filters registration charge item by creation date | `DATE = '2025-12-29'` |
+
+---
+
+## Query
+
+```sql
+SELECT
+  COUNT(*) AS total_registrations,
+  SUM(emr_chargeitem.total_price) AS total_revenue
+FROM emr_chargeitem
+WHERE emr_chargeitem.deleted = FALSE
+  AND emr_chargeitem.title = 'Registration Fee'
+--   [[AND {{date}}]];
+```
+
+
+## Notes
+
+- Only includes active charge items (deleted = FALSE)
+- Filters specifically for 'Registration Fee' title
+
+*Last updated: 2025-12-29*